Building Insulation

ABSTRACT

A building structure containing a building envelope that defines an interior is provided. The building structure includes building insulation positioned adjacent to a surface of the building envelope, the interior, or a combination thereof. The building insulation may include a porous polymeric material that is formed from a thermoplastic composition containing a continuous phase that includes a matrix polymer. A microinclusion additive and nanoinclusion additive may also be dispersed within the continuous phase in the form of discrete domains, wherein a porous network is defined in the material that includes a plurality of nanopores having an average cross-sectional dimension of about 800 nanometers or less.

RELATED APPLICATIONS

The present application claims priority to U.S. provisional applicationSer. No. 61/834,038, filed on Jun. 12, 2013, which is incorporatedherein in its entirety by reference thereto.

BACKGROUND OF THE INVENTION

Insulation is employed in building structures for a wide variety ofpurposes, such as for protection against heat transfer, moisture, noise,vibration, etc. One type of building insulation, for instance, is awater-impermeable housewrap used in the construction of wall and roofassemblies. In addition to preventing the entrance of water into thebuilding, such housewraps are also typically breathable to the extentthey are permeable to gases and can allow water vapor to escape from theinsulation rather than becoming trapped on a building surface.Unfortunately, one of the common problems associated with manyconventional types of building insulation, such as housewraps, is thatthey are not generally multi-functional. For example, a conventionalbreathable housewrap material is a flash spun polyolefin materialavailable from DuPont under the designation Tyvek®. While providing goodwater barrier properties, Tyvek® housewraps do not generally provide agood thermal barrier. To this end, polymeric foams are often employedfor the purpose of thermal insulation. However, such materials do notnecessarily function well as a breathable water barrier. Furthermore,the gaseous blowing agents used to form the foams can leach out of theinsulation over time, causing an environmental concern.

As such, a need currently exists for an improved insulation material foruse in building structures.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, buildinginsulation for use in a residential or commercial building structure isdisclosed. The building insulation includes a porous polymeric materialthat is formed from a thermoplastic composition containing a continuousphase that includes a matrix polymer. The polymeric material exhibits awater vapor transmission rate of about 300 g/m²-24 hours or more,thermal conductivity of about 0.40 watts per meter-kelvin or less,and/or hydrohead value of about 50 centimeters or more.

In accordance with one embodiment of the present invention, buildinginsulation for use in a residential or commercial building structure isdisclosed. The building insulation includes a porous polymeric materialthat is formed from a thermoplastic composition containing a continuousphase that includes a matrix polymer. A microinclusion additive andnanoinclusion additive are dispersed within the continuous phase in theform of discrete domains, wherein a porous network is defined in thematerial that includes a plurality of nanopores having an averagecross-sectional dimension of about 800 nanometers or less.

In accordance with yet another embodiment, a building structure isdisclosed that comprises a building envelope that defines an interior.The building structure further comprises building insulation, such asdescribed herein, which is positioned adjacent to a surface of thebuilding envelope, the interior, or a combination thereof. For example,in one embodiment, the building insulation may be positioned adjacent toa surface of the building envelope, such as adjacent to an exteriorwall, roof, or a combination thereof. If desired, the buildinginsulation may also be positioned adjacent to an exterior covering(e.g., siding). The building insulation may also be positioned adjacentto a surface of the interior, such as adjacent to an interior wall,floor, ceiling, door, or a combination thereof.

Other features and aspects of the present invention are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures in which:

FIG. 1 shows a partial representative view of a building foundation wallfabricated with a building panel that may be formed in accordance withthe invention;

FIG. 2 is an average cross-sectional dimension of the building panel ofFIG. 1 along a line 2-2;

FIG. 3 is a perspective view of one embodiment of a building structurein which the building insulation of the present invention is positionedadjacent to an exterior wall;

FIG. 4 is a perspective view of one embodiment of a building structurein which the building insulation of the present invention is positionedadjacent to an interior wall;

FIGS. 5-6 are SEM microphotographs of the unstretched film of Example 7(film was cut parallel to machine direction orientation);

FIGS. 7-8 are SEM microphotographs of the stretched film of Example 7(film was cut parallel to machine direction orientation);

FIGS. 9-10 are SEM microphotographs of the unstretched film of Example8, where the film was cut perpendicular to the machine direction in FIG.9 and parallel to the machine direction in FIG. 10;

FIGS. 11-12 are SEM microphotographs of the stretched film of Example 8(film was cut parallel to machine direction orientation);

FIG. 13 is an SEM photomicrograph (1,000×) of the fiber of Example 9(polypropylene, polylactic acid, and polyepoxide) after freezefracturing in liquid nitrogen;

FIG. 14 is an SEM photomicrograph (5,000×) of the fiber of Example 9(polypropylene, polylactic acid, and polyepoxide) after freezefracturing in liquid nitrogen; and

FIG. 15 is an SEM photomicrograph (10,000×) of the fiber surface ofExample 9 (polypropylene, polylactic acid, and polyepoxide).

Repeat use of references characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations may be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment, may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally speaking, the present invention is directed to buildinginsulation that contains a porous polymeric material (e.g., film,fibrous material, etc.). As used herein, the term “building insulation”refers broadly to any object in a building used as insulation for anypurpose, such as for thermal insulation, acoustic insulation, impactinsulation (e.g., for vibrations), fire insulation, moisture insulation,etc., as well as combinations thereof. The building insulation may bepositioned in a residential or commercial building structure so that itis adjacent to a surface of the building envelope, which is the physicalseparator between the interior and the exterior environments of abuilding and may include, for instance, the foundation, roof, exteriorwalls, exterior doors, windows, skylights, etc. The building insulationmay also be positioned adjacent to an interior surface of the building,such as an interior wall, interior door, flooring, ceilings, etc.

Regardless of the particular location in which the building insulationis employed, the porous polymeric material of the present invention mayserve multiple insulative functions within the building, and in somecases, even eliminating the need for certain types of conventionalinsulation. For instance, the polymeric material is porous and defines aporous network which, for instance, may constitute from about 15% toabout 80% per cm³, in some embodiments from about 20% to about 70%, andin some embodiments, from about 30% to about 60% per cubic centimeter ofthe material. The presence of such a high pore volume can allow thepolymeric material to be generally permeable to water vapors, therebyallowing such vapors to escape from a building surface during use andlimit the likelihood of water damage over time. The permeability of thematerial to water vapor may characterized by its relatively high watervapor transmission rate (“WVTR”), which is the rate at which water vaporpermeates through a material as measured in units of grams per metersquared per 24 hours (g/m²/24 hrs). For example, the polymeric materialmay exhibit a WVTR of about 300 g/m²-24 hours or more, in someembodiments about 500 g/m²-24 hours or more, in some embodiments about1,000 g/m²-24 hours or more, and in some embodiments, from about 3,000to about 15,000 g/m²-24 hours, such as determined in accordance withASTM E96/96M-12, Procedure B or INDA Test Procedure IST-70.4 (01). Inaddition to allowing the passage of vapors, the relatively high porevolume of the material can also significantly lower the density of thematerial, which can allow the use of lighter, more flexible materialsthat still achieve good insulative properties. For example, thecomposition may have a relatively low density, such as about 1.2 gramsper cubic centimeter (“g/cm³”) or less, in some embodiments about 1.0g/cm³ or less, in some embodiments from about 0.2 g/cm³ to about 0.8g/cm³, and in some embodiments, from about 0.1 g/cm³ to about 0.5 g/cm³.Due to its low density, lighter materials may be formed that stillachieve good thermal resistance.

Despite being highly porous and generally permeable to water vapor, thepresent inventors have nevertheless discovered that the porous networkmay be considered a “closed-cell” network such that a tortuous pathwayis not defined between a substantial portion of the pores. Such astructure can help restrict the flow of fluids through the material andbe generally impermeable to fluids (e.g., liquid water), therebyallowing the material to insulate a surface from water penetration. Inthis regard, the polymeric material may have a relatively high hydroheadvalue of about 50 centimeters (“cm”) or more, in some embodiments about100 cm or more, in some embodiments, about 150 cm or more, and in someembodiments, from about 200 cm to about 1000 cm, as determined inaccordance with ATTCC 127-2008.

A substantial portion of pores in the polymeric material may also be ofa “nano-scale” size (“nanopores”), such as those having an averagecross-sectional dimension of about 800 nanometers or less, in someembodiments from about 1 to about 500 nanometers, in some embodimentsfrom about 5 to about 450 nanometers, in some embodiments from about 5to about 400 nanometers, and in some embodiments, from about 10 to about100 nanometers. The term “cross-sectional dimension” generally refers toa characteristic dimension (e.g., width or diameter) of a pore, which issubstantially orthogonal to its major axis (e.g., length) and alsotypically substantially orthogonal to the direction of the stressapplied during drawing. Such nanopores may, for example, constituteabout 15 vol. % or more, in some embodiments about 20 vol. % or more, insome embodiments from about 30 vol. % to 100 vol. %, and in someembodiments, from about 40 vol. % to about 90 vol. % of the total porevolume in the polymeric material. The presence of such a high degree ofnanopores can substantially decrease thermal conductivity as fewer cellmolecules are available within each pore to collide and transfer heat.Thus, the polymeric material may also serve as thermal insulation tohelp limit the degree of heat transfer through the building structure.

To this end, the polymeric material may exhibit a relatively low thermalconductivity, such as about 0.40 watts per meter-kelvin (“W/m-K”) orless, in some embodiments about 0.20 W/m-K or less, in some embodimentsabout 0.15 W/m-K or less, in some embodiments from about 0.01 to about0.12 W/m-K, and in some embodiments, from about 0.02 to about 0.10W/m-K. Notably, the material is capable of achieving such low thermalconductivity values at relatively low thicknesses, which can allow thematerial to possess a greater degree of flexibility and conformability,as well as reduce the space it occupies in a building. For this reason,the polymeric material may also exhibit a relatively low “thermaladmittance”, which is equal to the thermal conductivity of the materialdivided by its thickness and is provided in units of watts per squaremeter-kelvins (“W/m²K”). For example, the material may exhibit a thermaladmittance of about 1000 W/m²K or less, in some embodiments from about10 to about 800 W/m²K, in some embodiments from about 20 to about 500W/m²K, and in some embodiments, from about 40 to about 200 W/m²K. Theactual thickness of the polymeric material may depend on its particularform, but typically ranges from about 5 micrometers to about 100millimeters, in some embodiments from about 10 micrometers to about 50millimeters, in some embodiments from about 200 micrometers to about 25millimeters, and in some embodiments, from about 50 micrometers to about5 millimeters.

Contrary to conventional techniques for forming building insulationmaterials, the present inventors have discovered that the porousmaterial of the present invention can be formed without the use ofgaseous blowing agents. This is due in part to the unique nature of thecomponents of the material, as well as the matter in which the materialis formed. More particularly, the porous material may be formed from athermoplastic composition containing a continuous phase that includes amatrix polymer, microinclusion additive, and nanoinclusion additive. Theadditives may be selected so that they have a different elastic modulusthan the matrix polymer. In this manner, the microinclusion andnanoinclusion additives can become dispersed within the continuous phaseas discrete micro-scale and nano-scale phase domains, respectively. Thepresent inventors have discovered that the micro-scale and nano-scalephase domains are able to interact in a unique manner when subjected toa deformation and elongational strain (e.g., drawing) to create anetwork of pores, a substantial portion of which are of a nano-scalesize. Namely, it is believed that elongational strain can initiateintensive localized shear zones and/or stress intensity zones (e.g.,normal stresses) near the micro-scale discrete phase domains as a resultof stress concentrations that arise from the incompatibility of thematerials. These shear and/or stress intensity zones cause some initialdebonding in the polymer matrix adjacent to the micro-scale domains.Notably, however, localized shear and/or stress intensity zones may alsobe created near the nano-scale discrete phase domains that overlap withthe micro-scale zones. Such overlapping shear and/or stress intensityzones cause even further debonding to occur in the polymer matrix,thereby creating a substantial number of nanopores adjacent to thenano-scale domains and/or micro-scale domains.

Various embodiments of the present invention will now be described inmore detail.

I. Thermoplastic Composition

A. Matrix Polymer

As indicated above, the thermoplastic composition may contain acontinuous phase that contains one or more matrix polymers, whichtypically constitute from about 60 wt. % to about 99 wt. %, in someembodiments from about 75 wt. % to about 98 wt. %, and in someembodiments, from about 80 wt. % to about 95 wt. % of the thermoplasticcomposition. The nature of the matrix polymer(s) used to form thecontinuous phase is not critical and any suitable polymer may generallybe employed, such as polyesters, polyolefins, styrenic polymers,polyamides, etc. In certain embodiments, for example, polyesters may beemployed in the composition to form the polymer matrix. Any of a varietyof polyesters may generally be employed, such as aliphatic polyesters,such as polycaprolactone, polyesteramides, polylactic acid (PLA) and itscopolymers, polyglycolic acid, polyalkylene carbonates (e.g.,polyethylene carbonate), poly-3-hydroxybutyrate (PHB),poly-3-hydroxyvalerate (PHV),poly-3-hydroxybutyrate-co-4-hydroxybutyrate,poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (PHBV),poly-3-hydroxybutyrate-co-3-hydroxyhexanoate,poly-3-hydroxybutyrate-co-3-hydroxyoctanoate,poly-3-hydroxybutyrate-co-3-hydroxydecanoate,poly-3-hydroxybutyrate-co-3-hydroxyoctadecanoate, and succinate-basedaliphatic polymers (e.g., polybutylene succinate, polybutylene succinateadipate, polyethylene succinate, etc.); aliphatic-aromatic copolyesters(e.g., polybutylene adipate terephthalate, polyethylene adipateterephthalate, polyethylene adipate isophthalate, polybutylene adipateisophthalate, etc.); aromatic polyesters (e.g., polyethyleneterephthalate, polybutylene terephthalate, etc.); and so forth.

In certain cases, the thermoplastic composition may contain at least onepolyester that is rigid in nature and thus has a relatively high glasstransition temperature. For example, the glass transition temperature(“T_(g)”) may be about 0° C. or more, in some embodiments from about 5°C. to about 100° C., in some embodiments from about 30° C. to about 80°C., and in some embodiments, from about 50° C. to about 75° C. Thepolyester may also have a melting temperature of from about 140° C. toabout 300° C., in some embodiments from about 150° C. to about 250° C.,and in some embodiments, from about 160° C. to about 220° C. The meltingtemperature may be determined using differential scanning calorimetry(“DSC”) in accordance with ASTM D-3417. The glass transition temperaturemay be determined by dynamic mechanical analysis in accordance with ASTME1640-09.

One particularly suitable rigid polyester is polylactic acid, which maygenerally be derived from monomer units of any isomer of lactic acid,such as levorotory-lactic acid (“L-lactic acid”), dextrorotatory-lacticacid (“D-lactic acid”), meso-lactic acid, or mixtures thereof. Monomerunits may also be formed from anhydrides of any isomer of lactic acid,including L-lactide, D-lactide, meso-lactide, or mixtures thereof.Cyclic dimers of such lactic acids and/or lactides may also be employed.Any known polymerization method, such as polycondensation orring-opening polymerization, may be used to polymerize lactic acid. Asmall amount of a chain-extending agent (e.g., a diisocyanate compound,an epoxy compound or an acid anhydride) may also be employed. Thepolylactic acid may be a homopolymer or a copolymer, such as one thatcontains monomer units derived from L-lactic acid and monomer unitsderived from D-lactic acid. Although not required, the rate of contentof one of the monomer unit derived from L-lactic acid and the monomerunit derived from D-lactic acid is preferably about 85 mole % or more,in some embodiments about 90 mole % or more, and in some embodiments,about 95 mole % or more. Multiple polylactic acids, each having adifferent ratio between the monomer unit derived from L-lactic acid andthe monomer unit derived from D-lactic acid, may be blended at anarbitrary percentage. Of course, polylactic acid may also be blendedwith other types of polymers (e.g., polyolefins, polyesters, etc.).

In one particular embodiment, the polylactic acid has the followinggeneral structure:

One specific example of suitable polylactic acid polymer that may beused in the present invention is commercially available from Biomer,Inc. of Krailling, Germany) under the name BIOMER™ L9000 Other suitablepolylactic acid polymers are commercially available from Natureworks LLCof Minnetonka, Minn. (NATUREWORKS®) or Mitsui Chemical (LACEA™). Stillother suitable polylactic acids may be described in U.S. Pat. Nos.4,797,468; 5,470,944; 5,770,682; 5,821,327; 5,880,254; and 6,326,458.

The polylactic acid typically has a number average molecular weight(“M_(n)”) ranging from about 40,000 to about 180,000 grams per mole, insome embodiments from about 50,000 to about 160,000 grams per mole, andin some embodiments, from about 80,000 to about 120,000 grams per mole.Likewise, the polymer also typically has a weight average a molecularweight (“M_(w)”) ranging from a bout 50,000 to about 250,000 g rams permole, in some embodiments from about 100,000 to about 200,000 grams permole, and in some embodiments, from about 110,000 to about 160,000 gramsper mole. The ratio of the Weight average molecular weight to the numberaverage molecular weight (“M_(w)/M_(n)”), i.e., the “polydispersityindex”, is also relatively low. For example, the polydispersity indextypically ranges from about 1.0 to about 3.0, in some embodiments fromabout 1.1 to about 2.0, and in some embodiments, from about 1.2 to about1.8. The weight and number average molecular weights may be determinedby methods known to those skilled in the art.

The polylactic acid may also have an apparent viscosity of from about 50to about 600 Pascal seconds (Pa·s), in some embodiments from about 100to about 500 Pa·s, and in some embodiments, from about 200 to about 400Pa·s, as determined at a temperature of 190° C. and a shear rate of 1000sec⁻¹. The melt flow rate of the polylactic acid (on a dry basis) mayalso range from about 0.1 to about 40 grams per 10 minutes, in someembodiments from about 0.5 to about 20 grams per 10 minutes, and in someembodiments, from about 5 to about 15 grams per 10 minutes, determinedat a load of 2160 grams and at 190° C.

Some types of neat polyesters (e.g., polylactic acid) can absorb waterfrom the ambient environment such that it has a moisture content ofabout 500 to 600 parts per million (“ppm”), or even greater, based onthe dry weight of the starting polylactic acid. Moisture content may bedetermined in a variety of ways as is known in the art, such as inaccordance with ASTM D 7191-05, such as described below. Because thepresence of water during melt processing can hydrolytically degrade thepolyester and reduce its molecular weight, it is sometimes desired todry the polyester prior to blending. In most embodiments, for example,it is desired that the polyester have a moisture content of about 300parts per million (“ppm”) or less, in some embodiments about 200 ppm orless, in some embodiments from about 1 to about 100 ppm prior toblending with the microinclusion and nanoinclusion additives. Drying ofthe polyester may occur, for instance, at a temperature of from about50° C. to about 100° C., and in some embodiments, from about 70° C. toabout 80° C.

B. Microinclusion Additive

As indicated above, in certain embodiments of the present invention,microinclusion and/or nanoinclusion additives may be dispersed withinthe continuous phase of the thermoplastic composition. As used herein,the term “microinclusion additive” generally refers to any amorphous,crystalline, or semi-crystalline material that is capable of beingdispersed within the polymer matrix in the form of discrete domains of amicro-scale size. For example, prior to drawing, the domains may have anaverage cross-sectional dimension of from about 0.05 μm to about 30 μm,in some embodiments from about 0.1 μm to about 25 μm, in someembodiments from about 0.5 μm to about 20 μm, and in some embodimentsfrom about 1 μm to about 10 μm. The term “cross-sectional dimension”generally refers to a characteristic dimension (e.g., width or diameter)of a domain, which is substantially orthogonal to its major axis (e.g.,length) and also typically substantially orthogonal to the direction ofthe stress applied during drawing. While typically formed from themicroinclusion additive, it should be also understood that themicro-scale domains may also be formed from a combination of themicroinclusion and nanoinclusion additives and/or other components ofthe composition.

The microinclusion additive is generally polymeric in nature andpossesses a relatively high molecular weight to help improve the meltstrength and stability of the thermoplastic composition. Typically, themicroinclusion polymer may be generally immiscible with the matrixpolymer. In this manner, the additive can better become dispersed asdiscrete phase domains within a continuous phase of the matrix polymer.The discrete domains are capable of absorbing energy that arises from anexternal force, which increases the overall toughness and strength ofthe resulting material. The domains may have a variety of differentshapes, such as elliptical, spherical, cylindrical, plate-like, tubular,etc. In one embodiment, for example, the domains have a substantiallyelliptical shape. The physical dimension of an individual domain istypically small enough to minimize the propagation of cracks through thepolymeric material upon the application of an external stress, but largeenough to initiate microscopic plastic deformation and allow for shearand/or stress intensity zones at and around particle inclusions.

While the polymers may be immiscible, the microinclusion additive maynevertheless be selected to have a solubility parameter that isrelatively similar to that of the matrix polymer. This can improve theinterfacial compatibility and physical interaction of the boundaries ofthe discrete and continuous phases, and thus reduces the likelihood thatthe composition will fracture. In this regard, the ratio of thesolubility parameter for the matrix polymer to that of the additive istypically from about 0.5 to about 1.5, and in some embodiments, fromabout 0.8 to about 1.2. For example, the microinclusion additive mayhave a solubility parameter of from about 15 to about 30MJoules^(1/2)/m^(3/2), and in some embodiments, from about 18 to about22 MJoules^(1/2)/m^(3/2), while polylactic acid may have a solubilityparameter of about 20.5 MJoules^(1/2)/m^(3/2). The term “solubilityparameter” as used herein refers to the “Hildebrand SolubilityParameter”, which is the square root of the cohesive energy density andcalculated according to the following equation:

δ=√((ΔH _(v) −RT)/V _(m))

where:

-   -   ΔHv=heat of vaporization    -   R=Ideal Gas constant    -   T=Temperature    -   Vm=Molecular Volume

The Hildebrand solubility parameters for many polymers are alsoavailable from the Solubility Handbook of Plastics, by Wyeych (2004),which is incorporated herein by reference.

The microinclusion additive may also have a certain melt flow rate (orviscosity) to ensure that the discrete domains and resulting pores canbe adequately maintained. For example, if the melt flow rate of theadditive is too high, it tends to flow and disperse uncontrollablythrough the continuous phase. This results in lamellar, plate-likedomains or co-continuous phase structures that are difficult to maintainand also likely to prematurely fracture. Conversely, if the melt flowrate of the additive is too low, it tends to clump together and formvery large elliptical domains, which are difficult to disperse duringblending. This may cause uneven distribution of the additive through theentirety of the continuous phase. In this regard, the present inventorshave discovered that the ratio of the melt flow rate of themicroinclusion additive to the melt flow rate of the matrix polymer istypically from about 0.2 to about 8, in some embodiments from about 0.5to about 6, and in some embodiments, from about 1 to about 5. Themicroinclusion additive may, for example, have a melt flow rate of fromabout 0.1 to about 250 grams per 10 minutes, in some embodiments fromabout 0.5 to about 200 grams per 10 minutes, and in some embodiments,from about 5 to about 150 grams per 10 minutes, determined at a load of2160 grams and at 190° C.

In addition to the properties noted above, the mechanicalcharacteristics of the microinclusion additive may also be selected toachieve the desired increase in toughness. For example, when a blend ofthe matrix polymer and microinclusion additive is applied with anexternal force, stress concentrations (e.g., including normal or shearstresses) and shear and/or plastic yielding zones may be initiated atand around the discrete phase domains as a result of stressconcentrations that arise from a difference in the elastic modulus ofthe additive and matrix polymer. Larger stress concentrations promotemore intensive localized plastic flow at the domains, which allows themto become significantly elongated when stresses are imparted. Theseelongated domains can allow the composition to exhibit a more pliableand softer behavior than the matrix polymer, such as when it is a rigidpolyester resin. To enhance the stress concentrations, themicroinclusion additive may be selected to have a relatively low Young'smodulus of elasticity in comparison to the matrix polymer. For example,the ratio of the modulus of elasticity of the matrix polymer to that ofthe additive is typically from about 1 to about 250, in some embodimentsfrom about 2 to about 100, and in some embodiments, from about 2 toabout 50. The modulus of elasticity of the microinclusion additive may,for instance, range from about 2 to about 1000 Megapascals (MPa), insome embodiments from about 5 to about 500 MPa, and in some embodiments,from about 10 to about 200 MPa. To the contrary, the modulus ofelasticity of polylactic acid, for example, is typically from about 800MPa to about 3000 MPa.

While a wide variety of microinclusion additives may be employed thathave the properties identified above, particularly suitable examples ofsuch additives may include synthetic polymers, such as polyolefins(e.g., polyethylene, polypropylene, polybutylene, etc.); styreniccopolymers (e.g., styrene-butadiene-styrene, styrene-isoprene-styrene,styrene-ethylene-propylene-styrene, styrene-ethylene-butadiene-styrene,etc.); polytetrafluoroethylenes; polyesters (e.g., recycled polyester,polyethylene terephthalate, etc.); polyvinyl acetates (e.g.,poly(ethylene vinyl acetate), polyvinyl chloride acetate, etc.);polyvinyl alcohols (e.g., polyvinyl alcohol, poly(ethylene vinylalcohol), etc.); polyvinyl butyrals; acrylic resins (e.g., polyacrylate,polymethylacrylate, polymethylmethacrylate, etc.); polyamides (e.g.,nylon); polyvinyl chlorides; polyvinylidene chlorides; polystyrenes;polyurethanes; etc. Suitable polyolefins may, for instance, includeethylene polymers (e.g., low density polyethylene (“LDPE”), high densitypolyethylene (“HDPE”), linear low density polyethylene (“LLDPE”), etc.),propylene homopolymers (e.g., syndiotactic, atactic, isotactic, etc.),propylene copolymers, and so forth.

In one particular embodiment, the polymer is a propylene polymer, suchas homopolypropylene or a copolymer of propylene. The propylene polymermay, for instance, be formed from a substantially isotacticpolypropylene homopolymer or a copolymer containing equal to or lessthan about 10 wt. % of other monomer, i.e., at least about 90% by weightpropylene. Such homopolymers may have a melting point of from about 160°C. to about 170° C.

In still another embodiment, the polyolefin may be a copolymer ofethylene or propylene with another α-olefin, such as a C₃-C₂₀ α-olefinor C₃-C₁₂ α-olefin. Specific examples of suitable α-olefins include1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentenewith one or more methyl, ethyl or propyl substituents; 1-hexene with oneor more methyl, ethyl or propyl substituents; 1-heptene with one or moremethyl, ethyl or propyl substituents; 1-octene with one or more methyl,ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl orpropyl substituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. Particularly desired α-olefin comonomers are1-butene, 1-hexene and 1-octene. The ethylene or propylene content ofsuch copolymers may be from about 60 mole % to about 99 mole %, in someembodiments from about 80 mole % to about 98.5 mole %, and in someembodiments, from about 87 mole % to about 97.5 mole %. The α-olefincontent may likewise range from about 1 mole % to about 40 mole %, insome embodiments from about 1.5 mole % to about 15 mole %, and in someembodiments, from about 2.5 mole % to about 13 mole %.

Exemplary olefin copolymers for use in the present invention includeethylene-based copolymers available under the designation EXACT™ fromExxonMobil Chemical Company of Houston, Tex. Other suitable ethylenecopolymers are available under the designation ENGAGE™, AFFINITY™,DOWLEX™ (LLDPE) and ATTANE™ (ULDPE) from Dow Chemical Company ofMidland, Mich. Other suitable ethylene polymers are described in U.S.Pat. No. 4,937,299 to Ewen et al.; U.S. Pat. No. 5,218,071 to Tsutsui etal.; U.S. Pat. No. 5,272,236 to Lai, et al.; and U.S. Pat. No. 5,278,272to Lai, et al. Suitable propylene copolymers are also commerciallyavailable under the designations VISTAMAXX™ from ExxonMobil Chemical Co.of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy,Belgium; TAFMER™ available from Mitsui Petrochemical Industries; andVERSIFY™ available from Dow Chemical Co. of Midland, Mich. Suitablepolypropylene homopolymers may likewise include Exxon Mobil 3155polypropylene, Exxon Mobil Achieve™ resins, and Total M3661 PP resin.Other examples of suitable propylene polymers are described in U.S. Pat.No. 6,500,563 to Datta, et al.; U.S. Pat. No. 5,539,056 to Yang, et al.;and U.S. Pat. No. 5,596,052 to Resconi, et al.

Any of a variety of known techniques may generally be employed to formthe olefin copolymers. For instance, olefin polymers may be formed usinga free radical or a coordination catalyst (e.g., Ziegler-Natta).Preferably, the olefin polymer is formed from a single-site coordinationcatalyst, such as a metallocene catalyst. Such a catalyst systemproduces ethylene copolymers in which the comonomer is randomlydistributed within a molecular chain and uniformly distributed acrossthe different molecular weight fractions. Metallocene-catalyzedpolyolefins are described, for instance, in U.S. Pat. No. 5,571,619 toMcAlpin et al.; U.S. Pat. No. 5,322,728 to Davis et al.; U.S. Pat. No.5,472,775 to Obijeski et al.; U.S. Pat. No. 5,272,236 to Lai et al.; andU.S. Pat. No. 6,090,325 to Wheat, et al. Examples of metallocenecatalysts include bis(n-butylcyclopentadienyl)titanium dichloride,bis(n-butylcyclopentadienyl)zirconium dichloride,bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconiumdichloride, bis(methylcyclopentadienyl)titanium dichloride,bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene,cyclopentadienytitanium trichloride, ferrocene, hafnocene dichloride,isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride,molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,titanocene dichloride, zirconocene chloride hydride, zirconocenedichloride, and so forth. Polymers made using metallocene catalyststypically have a narrow molecular weight range. For instance,metallocene-catalyzed polymers may have polydispersity numbers(M_(w)/M_(n)) of below 4, controlled short chain branching distribution,and controlled isotacticity.

Regardless of the materials employed, the relative percentage of themicroinclusion additive in the thermoplastic composition is selected toachieve the desired properties without significantly impacting the baseproperties of the composition. For example, the microinclusion additiveis typically employed in an amount of from about 1 wt. % to about 30 wt.%, in some embodiments from about 2 wt. % to about 25 wt. %, and in someembodiments, from about 5 wt. % to about 20 wt. % of the thermoplasticcomposition, based on the weight of the continuous phase (matrixpolymer(s)). The concentration of the microinclusion additive in theentire thermoplastic composition may likewise constitute from about 0.1wt. % to about 30 wt. %, in some embodiments from about 0.5 wt. % toabout 25 wt. %, and in some embodiments, from about 1 wt. % to about 20wt. %.

C. Nanoinclusion Additive

As used herein, the term “nanoinclusion additive” generally refers toany amorphous, crystalline, or semi-crystalline material that is capableof being dispersed within the polymer matrix in the form of discretedomains of a nano-scale size. For example, prior to drawing, the domainsmay have an average cross-sectional dimension of from about 1 to about500 nanometers, in some embodiments from about 2 to about 400nanometers, and in some embodiments, from about 5 to about 300nanometers. It should be also understood that the nano-scale domains mayalso be formed from a combination of the microinclusion andnanoinclusion additives and/or other components of the composition. Thenanoinclusion additive is typically employed in an amount of from about0.05 wt. % to about 20 wt. %, in some embodiments from about 0.1 wt. %to about 10 wt. %, and in some embodiments, from about 0.5 wt. % toabout 5 wt. % of the thermoplastic composition, based on the weight ofthe continuous phase (matrix polymer(s)). The concentration of thenanoinclusion additive in the entire thermoplastic composition maylikewise be from about 0.01 wt. % to about 15 wt. %, in some embodimentsfrom about 0.05 wt. % to about 10 wt. %, and in some embodiments, fromabout 0.3 wt. % to about 6 wt. % of the thermoplastic composition.

The nanoinclusion additive may be polymeric in nature and possess arelatively high molecular weight to help improve the melt strength andstability of the thermoplastic composition. To enhance its ability tobecome dispersed into nano-scale domains, the nanoinclusion additive mayalso be selected from materials that are generally compatible with thematrix polymer and the microinclusion additive. This may be particularlyuseful when the matrix polymer or the microinclusion additive possessesa polar moiety, such as a polyester. One example such a nanoinclusionadditive is a functionalized polyolefin. The polar component may, forexample, be provided by one or more functional groups and the non-polarcomponent may be provided by an olefin. The olefin component of thenanoinclusion additive may generally be formed from any linear orbranched α-olefin monomer, oligomer, or polymer (including copolymers)derived from an olefin monomer, such as described above.

The functional group of the nanoinclusion additive may be any group,molecular segment and/or block that provides a polar component to themolecule and is not compatible with the matrix polymer. Examples ofmolecular segment and/or blocks not compatible with polyolefin mayinclude acrylates, styrenics, polyesters, polyamides, etc. Thefunctional group can have an ionic nature and comprise charged metalions. Particularly suitable functional groups are maleic anhydride,maleic acid, fumaric acid, maleimide, maleic acid hydrazide, a reactionproduct of maleic anhydride and diamine, methylnadic anhydride,dichloromaleic anhydride, maleic acid amide, etc. Maleic anhydridemodified polyolefins are particularly suitable for use in the presentinvention. Such modified polyolefins are typically formed by graftingmaleic anhydride onto a polymeric backbone material. Such maleatedpolyolefins are available from E. I. du Pont de Nemours and Companyunder the designation Fusabond®, such as the P Series (chemicallymodified polypropylene), E Series (chemically modified polyethylene), CSeries (chemically modified ethylene vinyl acetate), A Series(chemically modified ethylene acrylate copolymers or terpolymers), or NSeries (chemically modified ethylene-propylene, ethylene-propylene dienemonomer (“EPDM”) or ethylene-octene). Alternatively, maleatedpolyolefins are also available from Chemtura Corp. under the designationPolybond® and Eastman Chemical Company under the designation Eastman Gseries.

In certain embodiments, the nanoinclusion additive may also be reactive.One example of such a reactive nanoinclusion additive is a polyepoxidethat contains, on average, at least two oxirane rings per molecule.Without intending to be limited by theory, it is believed that suchpolyepoxide molecules can induce reaction of the matrix polymer (e.g.,polyester) under certain conditions, thereby improving its melt strengthwithout significantly reducing glass transition temperature. Thereaction may involve chain extension, side chain branching, grafting,copolymer formation, etc. Chain extension, for instance, may occurthrough a variety of different reaction pathways. For instance, themodifier may enable a nucleophilic ring-opening reaction via a carboxylterminal group of a polyester (esterification) or via a hydroxyl group(etherification). Oxazoline side reactions may likewise occur to formesteramide moieties. Through such reactions, the molecular weight of thematrix polymer may be increased to counteract the degradation oftenobserved during melt processing. While it may be desirable to induce areaction with the matrix polymer as described above, the presentinventors have discovered that too much of a reaction can lead tocrosslinking between polymer backbones. If such crosslinking is allowedto proceed to a significant extent, the resulting polymer blend canbecome brittle and difficult to process into a material with the desiredstrength and elongation properties.

In this regard, the present inventors have discovered that polyepoxideshaving a relatively low epoxy functionality are particularly effective,which may be quantified by its “epoxy equivalent weight.” The epoxyequivalent weight reflects the amount of resin that contains onemolecule of an epoxy group, and it may be calculated by dividing thenumber average molecular weight of the modifier by the number of epoxygroups in the molecule. The polyepoxide of the present inventiontypically has a number average molecular weight from about 7,500 toabout 250,000 grams per mole, in some embodiments from about 15,000 toabout 150,000 grams per mole, and in some embodiments, from about 20,000to 100,000 grams per mole, with a polydispersity index typically rangingfrom 2.5 to 7. The polyepoxide may contain less than 50, in someembodiments from 5 to 45, and in some embodiments, from 15 to 40 epoxygroups. In turn, the epoxy equivalent weight may be less than about15,000 grams per mole, in some embodiments from about 200 to about10,000 grams per mole, and in some embodiments, from about 500 to about7,000 grams per mole.

The polyepoxide may be a linear or branched, homopolymer or copolymer(e.g., random, graft, block, etc.) containing terminal epoxy groups,skeletal oxirane units, and/or pendent epoxy groups. The monomersemployed to form such polyepoxides may vary. In one particularembodiment, for example, the polyepoxide contains at least oneepoxy-functional (meth)acrylic monomeric component. As used herein, theterm “(meth)acrylic” includes acrylic and methacrylic monomers, as wellas salts or esters thereof, such as acrylate and methacrylate monomers.For example, suitable epoxy-functional (meth)acrylic monomers mayinclude, but are not limited to, those containing 1,2-epoxy groups, suchas glycidyl acrylate and glycidyl methacrylate. Other suitableepoxy-functional monomers include allyl glycidyl ether, glycidylethacrylate, and glycidyl itoconate.

The polyepoxide typically has a relatively high molecular weight, asindicated above, so that it may not only result in chain extension, butalso help to achieve the desired blend morphology. The resulting meltflow rate of the polymer is thus typically within a range of from about10 to about 200 grams per 10 minutes, in some embodiments from about 40to about 150 grams per 10 minutes, and in some embodiments, from about60 to about 120 grams per 10 minutes, determined at a load of 2160 gramsand at a temperature of 190° C.

If desired, additional monomers may also be employed in the polyepoxideto help achieve the desired molecular weight. Such monomers may vary andinclude, for example, ester monomers, (meth)acrylic monomers, olefinmonomers, amide monomers, etc. In one particular embodiment, forexample, the polyepoxide includes at least one linear or branchedα-olefin monomer, such as those having from 2 to 20 carbon atoms andpreferably from 2 to 8 carbon atoms. Specific examples include ethylene,propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene;1-pentene; 1-pentene with one or more methyl, ethyl or propylsubstituents; 1-hexene with one or more methyl, ethyl or propylsubstituents; 1-heptene with one or more methyl, ethyl or propylsubstituents; 1-octene with one or more methyl, ethyl or propylsubstituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. Particularly desired α-olefin comonomers areethylene and propylene.

Another suitable monomer may include a (meth)acrylic monomer that is notepoxy-functional. Examples of such (meth)acrylic monomers may includemethyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate,n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate,n-amyl acrylate, i-amyl acrylate, isobornyl acrylate, n-hexyl acrylate,2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decylacrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexylacrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethylmethacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propylmethacrylate, i-butyl methacrylate, n-amyl methacrylate, n-hexylmethacrylate, i-amyl methacrylate, s-butyl-methacrylate, t-butylmethacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate,cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate,cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornylmethacrylate, etc., as well as combinations thereof.

In one particularly desirable embodiment of the present invention, thepolyepoxide is a terpolymer formed from an epoxy-functional(meth)acrylic monomeric component, α-olefin monomeric component, andnon-epoxy functional (meth)acrylic monomeric component. For example, thepolyepoxide may be poly(ethylene-co-methylacrylate-co-glycidylmethacrylate), which has the following structure:

wherein, x, y, and z are 1 or greater.

The epoxy functional monomer may be formed into a polymer using avariety of known techniques. For example, a monomer containing polarfunctional groups may be grafted onto a polymer backbone to form a graftcopolymer. Such grafting techniques are well known in the art anddescribed, for instance, in U.S. Pat. No. 5,179,164. In otherembodiments, a monomer containing epoxy functional groups may becopolymerized with a monomer to form a block or random copolymer usingknown free radical polymerization techniques, such as high pressurereactions, Ziegler-Natta catalyst reaction systems, single site catalyst(e.g., metallocene) reaction systems, etc.

The relative portion of the monomeric component(s) may be selected toachieve a balance between epoxy-reactivity and melt flow rate. Moreparticularly, high epoxy monomer contents can result in good reactivitywith the matrix polymer, but too high of a content may reduce the meltflow rate to such an extent that the polyepoxide adversely impacts themelt strength of the polymer blend. Thus, in most embodiments, theepoxy-functional (meth)acrylic monomer(s) constitute from about 1 wt. %to about 25 wt. %, in some embodiments from about 2 wt. % to about 20wt. %, and in some embodiments, from about 4 wt. % to about 15 wt. % ofthe copolymer. The α-olefin monomer(s) may likewise constitute fromabout 55 wt. % to about 95 wt. %, in some embodiments from about 60 wt.% to about 90 wt. %, and in some embodiments, from about 65 wt. % toabout 85 wt. % of the copolymer. When employed, other monomericcomponents (e.g., non-epoxy functional (meth)acrylic monomers) mayconstitute from about 5 wt. % to about 35 wt. %, in some embodimentsfrom about 8 wt. % to about 30 wt. %, and in some embodiments, fromabout 10 wt. % to about 25 wt. % of the copolymer. One specific exampleof a suitable polyepoxide that may be used in the present invention iscommercially available from Arkema under the name LOTADER® AX8950 orAX8900. LOTADER® AX8950, for instance, has a melt flow rate of 70 to 100g/10 min and has a glycidyl methacrylate monomer content of 7 wt. % to11 wt. %, a methyl acrylate monomer content of 13 wt. % to 17 wt. %, andan ethylene monomer content of 72 wt. % to 80 wt. %. Another suitablepolyepoxide is commercially available from DuPont under the nameELVALOY® PTW, which is a terpolymer of ethylene, butyl acrylate, andglycidyl methacrylate and has a melt flow rate of 12 g/10 min.

In addition to controlling the type and relative content of the monomersused to form the polyepoxide, the overall weight percentage may also becontrolled to achieve the desired benefits. For example, if themodification level is too low, the desired increase in melt strength andmechanical properties may not be achieved. The present inventors havealso discovered, however, that if the modification level is too high,processing may be restricted due to strong molecular interactions (e.g.,crosslinking) and physical network formation by the epoxy functionalgroups. Thus, the polyepoxide is typically employed in an amount of fromabout 0.05 wt. % to about 10 wt. %, in some embodiments from about 0.1wt. % to about 8 wt. %, in some embodiments from about 0.5 wt. % toabout 5 wt. %, and in some embodiments, from about 1 wt. % to about 3wt. %, based on the weight of the matrix polymer employed in thecomposition. The polyepoxide may also constitute from about 0.05 wt. %to about 10 wt. %, in some embodiments from about 0.05 wt. % to about 8wt. %, in some embodiments from about 0.1 wt. % to about 5 wt. %, and insome embodiments, from about 0.5 wt. % to about 3 wt. %, based on thetotal weight of the composition.

Other reactive nanoinclusion additives may also be employed in thepresent invention, such as oxazoline-functionalized polymers,cyanide-functionalized polymers, etc. When employed, such reactivenanoinclusion additives may be employed within the concentrations notedabove for the polyepoxide. In one particular embodiment, anoxazoline-grafted polyolefin may be employed that is a polyolefingrafted with an oxazoline ring-containing monomer. The oxazoline mayinclude a 2-oxazoline, such as 2-vinyl-2-oxazoline (e.g.,2-isopropenyl-2-oxazoline), 2-fatty-alkyl-2-oxazoline (e.g., obtainablefrom the ethanolamide of oleic acid, linoleic acid, palmitoleic acid,gadoleic acid, erucic acid and/or arachidonic acid) and combinationsthereof. In another embodiment, the oxazoline may be selected fromricinoloxazoline maleinate, undecyl-2-oxazoline, soya-2-oxazoline,ricinus-2-oxazoline and combinations thereof, for example. In yetanother embodiment, the oxazoline is selected from2-isopropenyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline andcombinations thereof.

Nanofillers may also be employed, such as carbon black, carbonnanotubes, carbon nanofibers, nanoclays, metal nanoparticles,nanosilica, nanoalumina, etc. Nanoclays are particularly suitable. Theterm “nanoclay” generally refers to nanoparticles of a clay material (anaturally occurring mineral, an organically modified mineral, or asynthetic nanomaterial), which typically have a platelet structure.Examples of nanoclays include, for instance, montmorillonite (2:1layered smectite day structure), bentonite (aluminium phyllosilicateformed primarily of montmorillonite), kaolinite (1:1 aluminosilicatehaving a platy structure and empirical formula of Al₂Si₂O₅(OH)₄),halloysite (1:1 aluminosilicate having a tubular structure and empiricalformula of Al₂Si₂O₅(OH)₄), etc. An example of a suitable nanoclay isCloisite®, which is a montmorillonite nanoclay and commerciallyavailable from Southern Clay Products, Inc. Other examples of syntheticnanoclays include but are not limited to a mixed-metal hydroxidenanoclay, layered double hydroxide nanoclay (e.g., sepiocite), laponite,hectorite, saponite, indonite, etc.

If desired, the nanoclay may contain a surface treatment to help improvecompatibility with the matrix polymer (e.g., polyester). The surfacetreatment may be organic or inorganic. In one embodiment, an organicsurface treatment is employed that is obtained by reacting an organiccation with the clay. Suitable organic cations may include, forinstance, organoquaternary ammonium compounds that are capable ofexchanging cations with the clay, such as dimethyl bis[hydrogenatedtallow]ammonium chloride (2M2HT), methyl benzyl bis[hydrogenatedtallow]ammonium chloride (MB2HT), methyl tris[hydrogenated tallowalkyl]chloride (M3HT), etc. Examples of commercially available organicnanoclays may include, for instance, Dellite® 43B (Laviosa Chimica ofLivorno, Italy), which is a montmorillonite clay modified with dimethylbenzylhydrogenated tallow ammonium salt. Other examples includeCloisite® 25A and Cloisite® 30B (Southern Clay Products) and Nanofil 919(Süd Chemie). If desired, the nanofiller can be blended with a carrierresin to form a masterbatch that enhances the compatibility of theadditive with the other polymers in the composition. Particularlysuitable carrier resins include, for instance, polyesters (e.g.,polylactic acid, polyethylene terephthalate, etc.); polyolefins (e.g.,ethylene polymers, propylene polymers, etc.); and so forth, as describedin more detail above.

In certain embodiments of the present invention, multiple nanoinclusionadditives may be employed in combination. For instance, a firstnanoinclusion additive (e.g., polyepoxide) may be dispersed in the formof domains having an average cross-sectional dimension of from about 50to about 500 nanometers, in some embodiments from about 60 to about 400nanometers, and in some embodiments from about 80 to about 300nanometers. A second nanoinclusion additive (e.g., nanofiller) may alsobe dispersed in the form of domains that are smaller than the firstnanoinclusive additive, such as those having an average cross-sectionaldimension of from about 1 to about 50 nanometers, in some embodimentsfrom about 2 to about 45 nanometers, and in some embodiments from about5 to about 40 nanometers. When employed, the first and/or secondnanoinclusion additives typically constitute from about 0.05 wt. % toabout 20 wt. %, in some embodiments from about 0.1 wt. % to about 10 wt.%, and in some embodiments, from about 0.5 wt. % to about 5 wt. % of thethermoplastic composition, based on the weight of the continuous phase(matrix polymer(s)). The concentration of the first and/or secondnanonclusion additives in the entire thermoplastic composition maylikewise be from about 0.01 wt. % to about 15 wt. %, in some embodimentsfrom about 0.05 wt. % to about 10 wt. %, and in some embodiments, fromabout 0.1 wt. % to about 8 wt. % of the thermoplastic composition.

D. Other Components

A wide variety of ingredients may be employed in the composition for avariety of different reasons. For instance, in one particularembodiment, an interphase modifier may be employed in the thermoplasticcomposition to help reduce the degree of friction and connectivitybetween the microinclusion additive and matrix polymer, and thus enhancethe degree and uniformity of debonding. In this manner, the pores canbecome distributed in a more homogeneous fashion throughout thecomposition. The modifier may be in a liquid or semi-solid form at roomtemperature (e.g., 25° C.) so that it possesses a relatively lowviscosity, allowing it to be more readily incorporated into thethermoplastic composition and to easily migrate to the polymer surfaces.In this regard, the kinematic viscosity of the interphase modifier istypically from about 0.7 to about 200 centistokes (“cs”), in someembodiments from about 1 to about 100 cs, and in some embodiments, fromabout 1.5 to about 80 cs, determined at 40° C. In addition, theinterphase modifier is also typically hydrophobic so that it has anaffinity for the microinclusion additive, for example, resulting in achange in the interfacial tension between the matrix polymer and theadditive. By reducing physical forces at the interfaces between thematrix polymer and the microinclusion additive, it is believed that thelow viscosity, hydrophobic nature of the modifier can help facilitatedebonding. As used herein, the term “hydrophobic” typically refers to amaterial having a contact angle of water in air of about 40° or more,and in some cases, about 60° or more. In contrast, the term“hydrophilic” typically refers to a material having a contact angle ofwater in air of less than about 40°. One suitable test for measuring thecontact angle is ASTM D5725-99 (2008).

Suitable hydrophobic, low viscosity interphase modifiers may include,for instance, silicones, silicone-polyether copolymers, aliphaticpolyesters, aromatic polyesters, alkylene glycols (e.g., ethyleneglycol, diethylene glycol, triethylene glycol, tetraethylene glycol,propylene glycol, polyethylene glycol, polypropylene glycol,polybutylene glycol, etc.), alkane diols (e.g., 1,3-propanediol,2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6 hexanediol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc.), amine oxides (e.g.,octyldimethylamine oxide), fatty acid esters, fatty acid amides (e.g.,oleamide, erucamide, stearamide, ethylene bis(stearamide), etc.),mineral, and vegetable oils, and so forth. One particularly suitableliquid or semi-solid is polyether polyol, such as commercially availableunder the trade name Pluriol® WI from BASF Corp. Another suitablemodifier is a partially renewable ester, such as commercially availableunder the trade name HALLGREEN® IM from Hallstar.

When employed, the interphase modifier may constitute from about 0.1 wt.% to about 20 wt. %, in some embodiments from about 0.5 wt. % to about15 wt. %, and in some embodiments, from about 1 wt. % to about 10 wt. %of the thermoplastic composition, based on the weight of the continuousphase (matrix polymer(s)). The concentration of the interphase modifierin the entire thermoplastic composition may likewise constitute fromabout 0.05 wt. % to about 20 wt. %, in some embodiments from about 0.1wt. % to about 15 wt. %, and in some embodiments, from about 0.5 wt. %to about 10 wt. %.

When employed in the amounts noted above, the interphase modifier has acharacter that enables it to readily migrate to the interfacial surfaceof the polymers and facilitate debonding without disrupting the overallmelt properties of the thermoplastic composition. For example, theinterphase modifier does not typically have a plasticizing effect on thepolymer by reducing its glass transition temperature. Quite to thecontrary, the present inventors have discovered that the glasstransition temperature of the thermoplastic composition may besubstantially the same as the initial matrix polymer. In this regard,the ratio of the glass temperature of the composition to that of thematrix polymer is typically from about 0.7 to about 1.3, in someembodiments from about 0.8 to about 1.2, and in some embodiments, fromabout 0.9 to about 1.1. The thermoplastic composition may, for example,have a glass transition temperature of from about 35° C. to about 80°C., in some embodiments from about 40° C. to about 80° C., and in someembodiments, from about 50° C. to about 65° C. The melt flow rate of thethermoplastic composition may also be similar to that of the matrixpolymer. For example, the melt flow rate of the composition (on a drybasis) may be from about 0.1 to about 70 grams per 10 minutes, in someembodiments from about 0.5 to about 50 grams per 10 minutes, and in someembodiments, from about 5 to about 25 grams per 10 minutes, determinedat a load of 2160 grams and at a temperature of 190° C.

Compatibilizers may also be employed that improve interfacial adhesionand reduce the interfacial tension between the domain and the matrix,thus allowing the formation of smaller domains during mixing. Examplesof suitable compatibilizers may include, for instance, copolymersfunctionalized with epoxy or maleic anhydride chemical moieties. Anexample of a maleic anhydride compatibilizer ispolypropylene-grafted-maleic anhydride, which is commercially availablefrom Arkema under the trade names Orevac™ 18750 and Orevac™ CA 100. Whenemployed, compatibilizers may constitute from about 0.05 wt. % to about10 wt. %, in some embodiments from about 0.1 wt. % to about 8 wt. %, andin some embodiments, from about 0.5 wt. % to about 5 wt. % of thethermoplastic composition, based on the weight of the continuous phasematrix.

Other suitable materials that may also be used in the thermoplasticcomposition, such as catalysts, antioxidants, stabilizers, surfactants,waxes, solid solvents, fillers, nucleating agents (e.g., calciumcarbonate, etc.), particulates, and other materials added to enhance theprocessability and mechanical properties of the thermoplasticcomposition. Nevertheless, one beneficial aspect of the presentinvention is that good properties may be provided without the need forvarious conventional additives, such as blowing agents (e.g.,chlorofluorocarbons, hydrochlorofluorocarbons, hydrocarbons, carbondioxide, supercritical carbon dioxide, nitrogen, etc.) and plasticizers(e.g., solid or semi-solid polyethylene glycol). In fact, thethermoplastic composition may be generally free of blowing agents and/orplasticizers. For example, blowing agents and/or plasticizers may bepresent in an amount of no more than about 1 wt. %, in some embodimentsno more than about 0.5 wt. %, and in some embodiments, from about 0.001wt. % to about 0.2 wt. % of the thermoplastic composition. Further, dueto its stress whitening properties, as described in more detail below,the resulting composition may achieve an opaque color (e.g., white)without the need for conventional pigments, such as titanium dioxide. Incertain embodiments, for example, pigments may be present in an amountof no more than about 1 wt. %, in some embodiments no more than about0.5 wt. %, and in some embodiments, from about 0.001 wt. % to about 0.2wt. % of the thermoplastic composition.

II. Polymeric Material

The polymeric material of the present invention may be formed by drawingthe thermoplastic composition, which may include the matrix polymer,microinclusion additive, nanoinclusion additive, as well as otheroptional components. To form the initial thermoplastic composition, thecomponents are typically blended together using any of a variety ofknown techniques. In one embodiment, for example, the components may besupplied separately or in combination. For instance, the components mayfirst be dry mixed together to form an essentially homogeneous drymixture, and they may likewise be supplied either simultaneously or insequence to a melt processing device that dispersively blends thematerials. Batch and/or continuous melt processing techniques may beemployed. For example, a mixer/kneader, Banbury mixer, Farrel continuousmixer, single-screw extruder, twin-screw extruder, roll mill, etc., maybe utilized to blend and melt process the materials. Particularlysuitable melt processing devices may be a co-rotating, twin-screwextruder (e.g., ZSK-30 extruder available from Werner & PfleidererCorporation of Ramsey, N.J. or a Thermo Prism™ USALAB 16 extruderavailable from Thermo Electron Corp., Stone, England). Such extrudersmay include feeding and venting ports and provide high intensitydistributive and dispersive mixing. For example, the components may befed to the same or different feeding ports of the twin-screw extruderand melt blended to form a substantially homogeneous melted mixture. Ifdesired, other additives may also be injected into the polymer meltand/or separately fed into the extruder at a different point along itslength.

Regardless of the particular processing technique chosen, the resultingmelt blended composition may contain micro-scale domains of themicroinclusion additive and nano-scale domains of the nanoinclusionadditive as described above. The degree of shear/pressure and heat maybe controlled to ensure sufficient dispersion, but not so high as toadversely reduce the size of the domains so that they are incapable ofachieving the desired properties. For example, blending typically occursat a temperature of from about 180° C. to about 300° C., in someembodiments from about 185° C. to about 250° C., and in someembodiments, from about 190° C. to about 240° C. Likewise, the apparentshear rate during melt processing may range from about 10 seconds⁻¹ toabout 3000 seconds⁻¹, in some embodiments from about 50 seconds⁻¹ toabout 2000 seconds⁻¹, and in some embodiments, from about 100 seconds⁻¹to about 1200 seconds⁻¹. The apparent shear rate may be equal to 4Q/πR³,where Q is the volumetric flow rate (“m³/s”) of the polymer melt and Ris the radius (“m”) of the capillary (e.g., extruder die) through whichthe melted polymer flows. Of course, other variables, such as theresidence time during melt processing, which is inversely proportionalto throughput rate, may also be controlled to achieve the desired degreeof homogeneity.

To achieve the desired shear conditions (e.g., rate, residence time,shear rate, melt processing temperature, etc.), the speed of theextruder screw(s) may be selected with a certain range. Generally, anincrease in product temperature is observed with increasing screw speeddue to the additional mechanical energy input into the system. Forexample, the screw speed may range from about 50 to about 600revolutions per minute (“rpm”), in some embodiments from about 70 toabout 500 rpm, and in some embodiments, from about 100 to about 300 rpm.This may result in a temperature that is sufficiently high to dispersethe microinclusion additive without adversely impacting the size of theresulting domains. The melt shear rate, and in turn the degree to whichthe additives are dispersed, may also be increased through the use ofone or more distributive and/or dispersive mixing elements within themixing section of the extruder. Suitable distributive mixers for singlescrew extruders may include, for instance, Saxon, Dulmage, CavityTransfer mixers, etc. Likewise, suitable dispersive mixers may includeBlister ring, Leroy/Maddock, CRD mixers, etc. As is well known in theart, the mixing may be further improved by using pins in the barrel thatcreate a folding and reorientation of the polymer melt, such as thoseused in Buss Kneader extruders, Cavity Transfer mixers, and VortexIntermeshing Pin (VIP) mixers.

Once blended, the porous network structure may be introduced by drawingthe composition in the longitudinal direction (e.g., machine direction),transverse direction (e.g., cross-machine direction), etc., as well ascombinations thereof. To perform the desired drawing, the thermoplasticcomposition may be formed into a precursor shape, drawn, and thereafterconverted into the desired material (e.g., film, fiber, etc.). In oneembodiment, the precursor shape may be a film having a thickness of fromabout 1 to about 5000 micrometers, in some embodiments from about 2 toabout 4000 micrometers, in some embodiments from about 5 to about 2500micrometers, and in some embodiments, from about 10 to about 500micrometers. As an alternative to forming a precursor shape, thethermoplastic composition may also be drawn in situ as it is beingshaped into the desired form for the polymeric material. In oneembodiment, for example, the thermoplastic composition may be drawn asit is being formed into a film or fiber.

Regardless, various drawing techniques may be employed, such asaspiration (e.g., fiber draw units), tensile frame drawing, biaxialdrawing, multi-axial drawing, profile drawing, vacuum drawing, etc. Inone embodiment, for example, the composition is drawn with a machinedirection orienter (“MDO”), such as commercially available from Marshalland Willams, Co. of Providence, R.I. MDO units typically have aplurality of drawing rolls (e.g., from 5 to 8) which progressively drawand thin the film in the machine direction. The composition may be drawnin either single or multiple discrete drawing operations. It should benoted that some of the rolls in an MDO apparatus may not be operating atprogressively higher speeds. To draw the composition in the mannerdescribed above, it is typically desired that the rolls of the MDO arenot heated. Nevertheless, if desired, one or more rolls may be heated toa slight extent to facilitate the drawing process so long as thetemperature of the composition remains below the ranges noted above.

The degree of drawing depends in part of the nature of the materialbeing drawn (e.g., fiber or film), but is generally selected to ensurethat the desired porous network is achieved. In this regard, thecomposition is typically drawn (e.g., in the machine direction) to adraw ratio of from about 1.1 to about 3.5, in some embodiments fromabout 1.2 to about 3.0, and in some embodiments, from about 1.3 to about2.5. The draw ratio may be determined by dividing the length of thedrawn material by its length before drawing. The draw rate may also varyto help achieve the desired properties, such as within the range of fromabout 5% to about 1500% per minute of deformation, in some embodimentsfrom about 20% to about 1000% per minute of deformation, and in someembodiments, from about 25% to about 850% per minute of deformation. Thecomposition is generally kept at a temperature below the glasstemperature of the matrix polymer and microinclusion additive duringdrawing. Among other things, this helps to ensure that the polymerchains are not altered to such an extent that the porous network becomesunstable. For example, the composition may be drawn at a temperaturethat is at least about 10° C., in some embodiments at least about 20°C., and in some embodiments, at least about 30° C. below the glasstransition temperature of the matrix polymer. For example, thecomposition may be drawn at a temperature of from about 0° C. to about50° C., in some embodiments from about 15° C. to about 40° C., and insome embodiments, from about 20° C. to about 30° C. Although thecomposition is typically drawn without the application of external heat(e.g., heated rolls), such heat might be optionally employed to improveprocessability, reduce draw force, increase draw rates, and improvefiber uniformity.

Drawing in the manner described above can result in the formation ofpores that have a “nano-scale” dimension (“nanopores”). For example, thenanopores may have an average cross-sectional dimension of about 800nanometers or less, in some embodiments from about 1 to about 500nanometers, in some embodiments from about 5 to about 450 nanometers, insome embodiments from about 5 to about 400 nanometers, and in someembodiments, from about 10 to about 100 nanometers. Micropores may alsobe formed at and around the micro-scale domains during drawing that havean average cross-sectional dimension of from about 0.5 to about 30micrometers, in some embodiments from about 1 to about 20 micrometers,and in some embodiments, from about 2 micrometers to about 15micrometers. The micropores and/or nanopores may have any regular orirregular shape, such as spherical, elongated, etc. In certain cases,the axial dimension of the micropores and/or nanopores may be largerthan the cross-sectional dimension so that the aspect ratio (the ratioof the axial dimension to the cross-sectional dimension) is from about 1to about 30, in some embodiments from about 1.1 to about 15, and in someembodiments, from about 1.2 to about 5. The “axial dimension” is thedimension in the direction of the major axis (e.g., length), which istypically in the direction of drawing.

The present inventors have also discovered that the pores (e.g.,micropores, nanopores, or both) can be distributed in a substantiallyhomogeneous fashion throughout the material. For example, the pores maybe distributed in columns that are oriented in a direction generallyperpendicular to the direction in which a stress is applied. Thesecolumns may be generally parallel to each other across the width of thematerial. Without intending to be limited by theory, it is believed thatthe presence of such a homogeneously distributed porous network canresult in a high thermal resistance as well as good mechanicalproperties (e.g., energy dissipation under load and impact strength).This is in stark contrast to conventional techniques for creating poresthat involve the use of blowing agents, which tend to result in anuncontrolled pore distribution and poor mechanical properties. Notably,the formation of the porous network by the process described above doesnot necessarily result in a substantial change in the cross-sectionalsize (e.g., width) of the material. In other words, the material is notsubstantially necked, which may allow the material to retain a greaterdegree of strength properties.

In addition to forming a porous network, drawing can also significantlyincrease the axial dimension of the micro-scale domains so that theyhave a generally linear, elongated shape. For example, the elongatedmicro-scale domains may have an average axial dimension that is about10% or more, in some embodiments from about 20% to about 500%, and insome embodiments, from about 50% to about 250% greater than the axialdimension of the domains prior to drawing. The axial dimension afterdrawing may, for instance, range from about 0.5 to about 250micrometers, in some embodiments from about 1 to about 100 micrometers,in some embodiments from about 2 to about 50 micrometers, and in someembodiments, from about 5 to about 25 micrometers. The micro-scaledomains may also be relatively thin and thus have a smallcross-sectional dimension, such as from about 0.05 to about 50micrometers, in some embodiments from about 0.2 to about 10 micrometers,and in some embodiments, from 0.5 to about 5 micrometers. This mayresult in an aspect ratio for the first domains (the ratio of the axialdimension to the cross-sectional dimension) of from about 2 to about150, in some embodiments from about 3 to about 100, and in someembodiments, from about 4 to about 50.

As a result of the porous and elongated domain structure, the presentinventors have discovered that the resulting polymeric material canexpand uniformly in volume when drawn in longitudinal direction, whichis reflected by a low “Poisson coefficient”, as determined according tothe following equation:

Poisson coefficient=−E _(transverse) /E _(longitudinal)

where E_(transverse) is the transverse deformation of the material andE_(longitudinal) is the longitudinal deformation of the material. Moreparticularly, the Poisson coefficient of the material can beapproximately 0 or even negative. For example, the Poisson coefficientmay be about 0.1 or less, in some embodiments about 0.08 or less, and insome embodiments, from about −0.1 to about 0.04. When the Poissoncoefficient is zero, there is no contraction in transverse directionwhen the material is expanded in the longitudinal direction. When thePoisson coefficient is negative, the transverse or lateral dimensions ofthe material are also expanding when the material is drawn in thelongitudinal direction. Materials having a negative Poisson coefficientcan thus exhibit an increase in width when drawn in the longitudinaldirection, which can result in increased energy absorption in the crossdirection.

The polymeric material of the present invention may generally have avariety of different forms depending on the particular application, suchas films, fibrous materials, molded articles, profiles, etc., as well ascomposites and laminates thereof, for use in building insulation. In oneembodiment, for example, the polymeric material is in the form of a filmor layer of a film. Multilayer films may contain from two (2) to fifteen(15) layers, and in some embodiments, from three (3) to twelve (12)layers. Such multilayer films normally contain at least one base layerand at least one additional layer (e.g., skin layer), but may containany number of layers desired. For example, the multilayer film may beformed from a base layer and one or more skin layers, wherein the baselayer and/or skin layer(s) are formed from the polymeric material of thepresent invention. It should be understood, however, that other polymermaterials may also be employed in the base layer and/or skin layer(s),such as polyolefin polymers.

The thickness of the film may be relatively small to increaseflexibility. For example, the film may have a thickness of from about 1to about 200 micrometers, in some embodiments from about 2 to about 150micrometers, in some embodiments from about 5 to about 100 micrometers,and in some embodiments, from about 10 to about 60 micrometers. Despitehaving such a small thickness, the film may nevertheless be able toretain good mechanical properties during use. For example, the film maybe relatively ductile. One parameter that is indicative of the ductilityof the film is the percent elongation of the film at its break point, asdetermined by the stress strain curve, such as obtained in accordancewith ASTM Standard D638-10 at 23° C. For example, the percent elongationat break of the film in the machine direction (“MD”) may be about 10% ormore, in some embodiments about 50% or more, in some embodiments about80% or more, and in some embodiments, from about 100% to about 600%.Likewise, the percent elongation at break of the film in thecross-machine direction (“CD”) may be about 15% or more, in someembodiments about 40% or more, in some embodiments about 70% or more,and in some embodiments, from about 100% to about 400%. Anotherparameter that is indicative of ductility is the tensile modulus of thefilm, which is equal to the ratio of the tensile stress to the tensilestrain and is determined from the slope of a stress-strain curve. Forexample, the film typically exhibits a MD and/or CD tensile modulus ofabout 2500 Megapascals (“MPa”) or less, in some embodiments about 2200MPa or less, in some embodiments from about 50 MPa to about 2000 MPa,and in some embodiments, from about 100 MPa to about 1000 MPa. Thetensile modulus may be determined in accordance with ASTM D638-10 at 23°C.

Although the film is ductile, it can still be relatively strong. Oneparameter that is indicative of the relative strength of the film is theultimate tensile strength, which is equal to the peak stress obtained ina stress-strain curve, such as obtained in accordance with ASTM StandardD638-10. For example, the film may exhibit an MD and/or CD peak stressof from about 5 to about 65 MPa, in some embodiments from about 10 MPato about 60 MPa, and in some embodiments, from about 20 MPa to about 55MPa. The film may also exhibit an MD and/or CD break stress of fromabout 5 MPa to about 60 MPa, in some embodiments from about 10 MPa toabout 50 MPa, and in some embodiments, from about 20 MPa to about 45MPa. The peak stress and break stress may be determined in accordancewith ASTM D638-10 at 23° C.

In addition to a film, the polymeric material may also be in the form ofa fibrous material or a layer or component of a fibrous material, whichcan include individual staple fibers or filaments (continuous fibers),as well as yarns, fabrics, etc. formed from such fibers. Yarns mayinclude, for instance, multiple staple fibers that are twisted together(“spun yam”), filaments laid together without twist (“zero-twist yarn”),filaments laid together with a degree of twist, single filament with orwithout twist (“monofilament”), etc. The yarn may or may not betexturized. Suitable fabrics may likewise include, for instance, wovenfabrics, knit fabrics, nonwoven fabrics (e.g., spunbond webs, meltblownwebs, bonded carded webs, wet-laid webs, airlaid webs, coform webs,hydraulically entangled webs, etc.), and so forth.

Fibers formed from the thermoplastic composition may generally have anydesired configuration, including monocomponent and multicomponent (e.g.,sheath-core configuration, side-by-side configuration, segmented pieconfiguration, island-in-the-sea configuration, and so forth). In someembodiments, the fibers may contain one or more additional polymers as acomponent (e.g., bicomponent) or constituent (e.g., biconstituent) tofurther enhance strength and other mechanical properties. For instance,the thermoplastic composition may form a sheath component of asheath/core bicomponent fiber, while an additional polymer may form thecore component, or vice versa. The additional polymer may be athermoplastic polymer such as polyesters, e.g., polylactic acid,polyethylene terephthalate, polybutylene terephthalate, and so forth;polyolefins, e.g., polyethylene, polypropylene, polybutylene, and soforth; polytetrafluoroethylene; polyvinyl acetate; polyvinyl chlorideacetate; polyvinyl butyral; acrylic resins, e.g., polyacrylate,polymethylacrylate, polymethylmethacrylate, and so forth; polyamides,e.g., nylon; polyvinyl chloride; polyvinylidene chloride; polystyrene;polyvinyl alcohol; and polyurethanes.

When employed, the fibers can deform upon the application of strain,rather than fracture. The fibers may thus continue to function as a loadbearing member even after the fiber has exhibited substantialelongation. In this regard, the fibers of the present invention arecapable of exhibiting improved “peak elongation properties, i.e., thepercent elongation of the fiber at its peak load. For example, thefibers of the present invention may exhibit a peak elongation of about50% or more, in some embodiments about 100% or more, in some embodimentsfrom about 200% to about 1500%, and in some embodiments, from about 400%to about 800%, such as determined in accordance with ASTM D638-10 at 23°C. Such elongations may be achieved for fibers having a wide variety ofaverage diameters, such as those ranging from about 0.1 to about 50micrometers, in some embodiments from about 1 to about 40 micrometers,in some embodiments from about 2 to about 25 micrometers, and in someembodiments, from about 5 to about 15 micrometers.

While possessing the ability to extend under strain, the fibers of thepresent invention can also remain relatively strong. For example, thefibers may exhibit a peak tensile stress of from about 25 to about 500Megapascals (“MPa”), in some embodiments from about 50 to about 300 MPa,and in some embodiments, from about 60 to about 200 MPa, such asdetermined in accordance with ASTM D638-10 at 23° C. Another parameterthat is indicative of the relative strength of the fibers of the presentinvention is “tenacity”, which indicates the tensile strength of a fiberexpressed as force per unit linear density. For example, the fibers ofthe present invention may have a tenacity of from about 0.75 to about6.0 grams-force (“g_(f)”) per denier, in some embodiments from about 1.0to about 4.5 g_(f) per denier, and in some embodiments, from about 1.5to about 4.0 g_(f) per denier. The denier of the fibers may varydepending on the desired application. Typically, the fibers are formedto have a denier per filament (i.e., the unit of linear density equal tothe mass in grams per 9000 meters of fiber) of less than about 6, insome embodiments less than about 3, and in some embodiments, from about0.5 to about 3.

If desired, the polymeric material of the present invention may besubjected to one or more additional processing steps, before and/orafter being drawn. Examples of such processes include, for instance,groove roll drawing, embossing, coating, etc. In certain embodiments,the polymeric material may also be annealed to help ensure that itretains the desired shape. Annealing typically occurs at or above theglass transition temperature of the polymer matrix, such as at fromabout 40° to about 120° C., in some embodiments from about 50° C. toabout 100° C., and in some embodiments, from about 70° C. to about 90°C. The polymeric material may also be surface treated using any of avariety of known techniques to improve its properties. For example, highenergy beams (e.g., plasma, x-rays, e-beam, etc.) may be used to removeor reduce any skin layers, to change the surface polarity, porosity,topography, to embrittle a surface layer, etc. If desired, such surfacetreatment may be used before and/or drawing of the thermoplasticcomposition.

III. Building Insulation

As indicated above, the building insulation of the present invention canbe used for a wide variety of purposes, such as for thermal insulation,acoustic insulation, impact insulation (e.g., for vibrations), fireinsulation, moisture insulation, etc., as well as combinations thereof.In certain embodiments, building insulation may be employed in astructure that is formed entirely from the polymeric material of thepresent invention. In other embodiments, however, the buildinginsulation may include the polymeric material as one layer and one ormore additional layers of material for a variety of purposes, such asfor additional insulation, barrier properties, or as a covering. Theadditional layer(s) may include other conventional types of materials,such as polymeric foams, films or sheets, nonwoven webs, fiberglassmaterials, cellulosic materials, scrims, foils, etc. Regardless of itsparticular construction, the building insulation may be positioned in aresidential or commercial building structure so that it is adjacent to asurface of the building envelope and/or adjacent to an interior surfaceof the building.

Building panels, for example, may be formed from the polymeric materialof the present invention and employed without limitation in theconstruction of foundation walls, frost walls (e.g., in buildings thathave no basement), manufactured home base curtain walls, floor systems,ceiling systems, roof systems, exterior above-grade walls, curtainwalls, exterior walls in areas that use masonry exteriors, etc.Referring to FIGS. 1-2, for instance, one embodiment of a building panel(e.g., foundation wall panel) that may be formed in accordance with thepresent invention is shown in more detail. As illustrated, a buildingcontains interior and exterior foundation walls 10 that collectivelydefine a foundation 12. Each foundation wall 10 is in turn defined byone or more foundation wall panels 14. In the illustration, eachfoundation wall panel 14 includes a bottom plate 16, an upstanding wallsection 18, and a top plate 20. Each upstanding wall section 18 includesa main-run wall section 22 and uprightly-oriented reinforcing studs 23affixed to, or integral with, the main-run wall section, regularlyspaced along the length of the wall section, and extending inwardly ofthe inner surface of the main run wall section. In the embodimentillustrated in FIG. 1, anchoring wedge-shaped brackets 24 are mounted tothe studs at the tops and bottoms of the wall section to assist inanchoring the bottom plate and the top plate, and/or any otherattachment, to the main run portion of the upstanding wall section.

As illustrated, conventional beams 26 (e.g., steel I-beams) are mountedto the wall sections, as needed, to support spans of overlying floors.Such beams can be supported as needed by posts 28 and/or pads 30.Additional support posts can also be employed at or adjacent the ends ofthe beams to satisfy specific, individual load-bearing requirements ofthe building design. Solid reinforcing studs 23 can be used to attachthe beams to respective panels of the foundation wall. As shown in FIG.2, a main run wall section 22 is generally defined between the innersurface and the outer surface of the wall panel 14. In accordance withone embodiment of the present invention, the wall section 22 may includethe polymeric material of the present invention as building insulation32, which provides a thermal barrier between the inwardly-facing surfaceof the wall and the outwardly-facing surface of the wall. Bottom plate16 and top plate 20 can be secured to the main run section 22 with thesupport of wedge-shaped brackets 24 or other supporting bracketstructure. The bottom plate 16 may support the foundation wall andoverlying building superstructure from an underlying fabricated base,such as a concrete footer 55.

In yet other embodiments of the present invention, the buildinginsulation of the present invention may be employed as a “housewrap”material that acts as an external sheathing for the building and islocated adjacent to an external surface (e.g., wall, roof, etc.) of thebuilding. For example, such materials may be applied to the externalsurface and/or to an exterior covering (e.g., siding, brick, stone,masonry, stucco, concrete veneers, etc.) prior to its installation andlocated adjacent thereto. Referring to FIG. 3, for instance, oneembodiment is shown in which the building insulation is applied to theexterior wall. Typically, the building insulation is employed after thewalls have been constructed and all sheathing and flashing details havebeen installed. The building insulation is preferably applied beforedoors and windows have been set Inside framed openings and prior to theinstallation of the primary wall covering. In the illustratedembodiment, a first building insulation 100 is applied to the wallassembly 140. As shown, a roll of the insulation material may beunrolled. The building insulation 100 is secured to the exterior wallassembly 140 with fasteners, such as staples or cap nails. The buildinginsulation may be trimmed around each framed opening with additionalappropriate detailing applied as per window/door manufacturer and/orcode standards. Once installed, an exterior covering may beapplied/installed over the building insulation if so desired.

Besides insulating an external surface of a building structure, thebuilding insulation may also be employed within the interior of abuilding. In such embodiments, the building insulation is typicallypositioned so that it is adjacent to an interior surface of thebuilding, such as the ceiling, floor, stud wall, interior door, etc.Referring to FIG. 4, for example, one embodiment of an interior surface250 that can be insulated in accordance with the present invention isshown. More particularly, FIG. 4 is intended to illustrate across-sectional view of an insulated wall cavity. In this embodiment,the surface 250 includes a wall that is attached to a pair of studs 252and 254. Between the pair of studs 252 and 254 is a layer of thebuilding insulation material 256 of the present invention, which isapplied to the surface 250. In the embodiment illustrated in FIG. 4, thebuilding insulation 256 is positioned directly adjacent to the surface250. It should be understood, however, that in other embodiments, anadditional type of insulation may be positioned in between the surface250 and the building insulation 256.

The present invention may be better understood with reference to thefollowing examples.

Test Methods Hydrostatic Pressure Test (“Hydrohead”):

The hydrostatic pressure test is a measure of the resistance of amaterial to penetration by liquid water under a static pressure and isperformed in accordance with AATCC Test Method 127-2008. The results foreach specimen may be averaged and recorded in centimeters (cm). A highervalue indicates greater resistance to water penetration.

Water Vapor Transmission Rate (“WVTR”):

The test used to determine the WVTR of a material may vary based on thenature of the material. One technique for measuring the WVTR value isASTM E96/96M-12, Procedure B. Another method involves the use of INDATest Procedure IST-70.4 (01). The INDA test procedure is summarized asfollows. A dry chamber is separated from a wet chamber of knowntemperature and humidity by a permanent guard film and the samplematerial to be tested. The purpose of the guard film is to define adefinite air gap and to quiet or still the air in the air gap while theair gap is characterized. The dry chamber, guard film, and the wetchamber make up a diffusion cell in which the test film is sealed. Thesample holder is known as the Permatran-W Model 100K manufactured byMocon/Modem Controls, Inc., Minneapolis, Minn. A first test is made ofthe WVTR of the guard film and the air gap between an evaporatorassembly that generates 100% relative humidity. Water vapor diffusesthrough the air gap and the guard film and then mixes with a dry gasflow that is proportional to water vapor concentration. The electricalsignal is routed to a computer for processing. The computer calculatesthe transmission rate of the air gap and the guard film and stores thevalue for further use.

The transmission rate of the guard film and air gap stored in thecomputer as CalC. The sample material is then sealed in the test cell.Again, water vapor diffuses through the air gap to the guard film andthe test material and then mixes with a dry gas flow that sweeps thetest material. Also, again, this mixture is carried to the vapor sensor.The computer then calculates the transmission rate of the combination ofthe air gap, the guard film, and the test material. This information isthen used to calculate the transmission rate at which moisture istransmitted through the test material according to the equation:

TR⁻ _(1test material)=TR⁻ _(1test material,guardfilm,airgap)−TR⁻¹_(guardfilm,airgap)

The water vapor transmission rate (“WVTR”) is then calculated asfollows:

${WVTR} = \frac{F\; \rho_{{sat}{(T)}}{RH}}{{AP}_{{sat}{(T)}}\left( {1 - {RH}} \right)}$

wherein,

F=the flow of water vapor in cm³ per minute;

ρ_(sat(T))=the density of water in saturated air at temperature T;

RH=the relative humidity at specified locations in the cell;

A=the cross sectional area of the cell; and

P_(sat(T))=the saturation vapor pressure of water vapor at temperatureT.

Conductive Properties:

Thermal conductivity (W/mK) and thermal resistance (m²K/W) may bedetermined in accordance with ASTM E-1530-11 (“Resistance to ThermalTransmission of Materials by the Guarded Heat Flow Meter Technique”)using an Anter Unitherm Model 2022 tester. The target test temperaturemay be 25° C. and the applied load may be 0.17 MPa. Prior to testing,the samples may be conditioned for 40+ hours at a temperature of 23° C.(±2° C.) and relative humidity of 50% (±10%). Thermal admittance (W/m²K)may also be calculated by dividing 1 by the thermal resistance.

Melt Flow Rate:

The melt flow rate (“MFR”) is the weight of a polymer (in grams) forcedthrough an extrusion rheometer orifice (0.0825-inch diameter) whensubjected to a load of 2160 grams in 10 minutes, typically at 190° C.,210° C., or 230° C. Unless otherwise indicated, melt flow rate ismeasured in accordance with ASTM Test Method D1239 with a Tinius OlsenExtrusion Plastometer.

Thermal Properties:

The glass transition temperature (T_(g)) may be determined by dynamicmechanical analysis (DMA) in accordance with ASTM E1640-09. A Q800instrument from TA Instruments may be used. The experimental runs may beexecuted in tension/tension geometry, in a temperature sweep mode in therange from −120° C. to 150° C. with a heating rate of 3° C./min. Thestrain amplitude frequency may be kept constant (2 Hz) during the test.Three (3) independent samples may be tested to get an average glasstransition temperature, which is defined by the peak value of the tan δcurve, wherein tan δ is defined as the ratio of the loss modulus to thestorage modulus (tan δ=E″/E′).

The melting temperature may be determined by differential scanningcalorimetry (DSC). The differential scanning calorimeter may be a DSCQ100 Differential Scanning Calorimeter, which may be outfitted with aliquid nitrogen cooling accessory and with a UNIVERSAL ANALYSIS 2000(version 4.6.6) analysis software program, both of which are availablefrom T.A. Instruments Inc. of New Castle, Del. To avoid directlyhandling the samples, tweezers or other tools may be used. The samplesmay be placed into an aluminum pan and weighed to an accuracy of 0.01milligram on an analytical balance. A lid may be crimped over thematerial sample onto the pan. Typically, the resin pellets may be placeddirectly in the weighing pan.

The differential scanning calorimeter may be calibrated using an indiummetal standard and a baseline correction may be performed, as describedin the operating manual for the differential scanning calorimeter. Amaterial sample may be placed into the test chamber of the differentialscanning calorimeter for testing, and an empty pan may be used as areference. All testing may be run with a 55-cubic centimeter per minutenitrogen (industrial grade) purge on the test chamber. For resin pelletsamples, the heating and cooling program is a 2-cycle test that beganwith an equilibration of the chamber to −30° C., followed by a firstheating period at a heating rate of 10° C. per minute to a temperatureof 200° C., followed by equilibration of the sample at 200° C. for 3minutes, followed by a first cooling period at a cooling rate of 10° C.per minute to a temperature of −30° C., followed by equilibration of thesample at −30° C. for 3 minutes, and then a second heating period at aheating rate of 10° C. per minute to a temperature of 200° C. For fibersamples, the heating and cooling program may be a 1-cycle test thatbegins with an equilibration of the chamber to −25° C., followed by aheating period at a heating rate of 10° C. per minute to a temperatureof 200° C., followed by equilibration of the sample at 200° C. for 3minutes, and then a cooling period at a cooling rate of 10° C. perminute to a temperature of −30° C. All testing may be run with a55-cubic centimeter per minute nitrogen (industrial grade) purge on thetest chamber.

The results may be evaluated using the UNIVERSAL ANALYSIS 2000 analysissoftware program, which identifies and quantifies the glass transitiontemperature (T_(g)) of inflection, the endothermic and exothermic peaks,and the areas under the peaks on the DSC plots. The glass transitiontemperature may be identified as the region on the plot-line where adistinct change in slope occurred, and the melting temperature may bedetermined using an automatic inflection calculation.

Film Tensile Properties:

Films may be tested for tensile properties (peak stress, modulus, strainat break, and energy per volume at break) on a MTS Synergie 200 tensileframe. The test may be performed in accordance with ASTM D638-10 (atabout 23° C.). Film samples may be cut into dog bone shapes with acenter width of 3.0 mm before testing. The dog-bone film samples may beheld in place using grips on the MTS Synergie 200 device with a gaugelength of 18.0 mm. The film samples may be stretched at a crossheadspeed of 5.0 in/min until breakage occurred. Five samples may be testedfor each film in both the machine direction (MD) and the cross direction(CD). A computer program (e.g., TestWorks 4) may be used to collect dataduring testing and to generate a stress versus strain curve from which anumber of properties may be determined, including modulus, peak stress,elongation, and energy to break.

Fiber Tensile Properties:

Fiber tensile properties may be determined in accordance with ASTM638-10 at 23° C. For instance, individual fiber specimens may initiallybe shortened (e.g., cut with scissors) to 38 millimeters in length, andplaced separately on a black velvet cloth. 10 to 15 fiber specimens maybe collected in this manner. The fiber specimens may then be mounted ina substantially straight condition on a rectangular paper frame havingexternal dimension of 51 millimeters×51 millimeters and internaldimension of 25 millimeters×25 millimeters. The ends of each fiberspecimen may be operatively attached to the frame by carefully securingthe fiber ends to the sides of the frame with adhesive tape. Each fiberspecimen may be measured for its external, relatively shorter,cross-fiber dimension employing a conventional laboratory microscope,which may be properly calibrated and set at 40× magnification. Thiscross-fiber dimension may be recorded as the diameter of the individualfiber specimen. The frame helps to mount the ends of the sample fiberspecimens in the upper and lower grips of a constant rate of extensiontype tensile tester in a manner that avoids excessive damage to thefiber specimens.

A constant rate of extension type of tensile tester and an appropriateload cell may be employed for the testing. The load cell may be chosen(e.g., 10N) so that the test value falls within 10-90% of the full scaleload. The tensile tester (i.e., MTS SYNERGY 200) and load cell may beobtained from MTS Systems Corporation of Eden Prairie, Mich. The fiberspecimens in the frame assembly may then be mounted between the grips ofthe tensile tester such that the ends of the fibers may be operativelyheld by the grips of the tensile tester. Then, the sides of the paperframe that extend parallel to the fiber length may be cut or otherwiseseparated so that the tensile tester applies the test force only to thefibers. The fibers may be subjected to a pull test at a pull rate andgrip speed of 12 inches per minute. The resulting data may be analyzedusing a TESTWORKS 4 software program from the MTS Corporation with thefollowing test settings:

Calculation Inputs Test Inputs Break mark drop 50% Break sensitivity 90%Break marker 0.1 in Break threshold 10 g_(f) elongation Data Acq. Rate10 Hz Nominal gage length   1 in Denier length 9000 m Slack pre-load 1lb_(f) Density 1.25 g/cm³ Slope segment length   20% Initial speed 12in/min Yield offset 0.20% Secondary speed  2 in/min Yield segment length  2%

The tenacity values may be expressed in terms of gram-force per denier.Peak elongation (% strain at break) and peak stress may also bemeasured.

Expansion Ratio, Density, and Percent Pore Volume:

To determine expansion ratio, density, and percent pore volume, thewidth (W) and thickness (T_(i)) of the specimen may be initiallymeasured prior to drawing. The length (L_(i)) before drawing may also bedetermined by measuring the distance between two markings on a surfaceof the specimen. Thereafter, the specimen may be drawn to initiatevoiding. The width (W_(f)), thickness (T_(f)), and length (L_(f)) of thespecimen may then be measured to the nearest 0.01 mm utilizing DigimaticCaliper (Mitutoyo Corporation). The volume (V_(i)) before drawing may becalculated by W_(i)×T_(i)×L_(i)=V_(i). The volume (V_(f)) after drawingmay also be calculated by W_(f)×T_(f)×L_(f)=V_(f). The expansion ratio(φ) may be calculated by φ=V_(f)/V_(i); the density (P_(f)) of wascalculated by: P_(f)=P_(i)/φ, where P_(i) is density of precursormaterial; and the percent pore volume (% V_(v)) may be calculated by: %V_(v)=(1−1/φ)×100.

Moisture Content:

Moisture content may be determined using an Arizona InstrumentsComputrac Vapor Pro moisture analyzer (Model No. 3100) in substantialaccordance with ASTM D 7191-05, which is incorporated herein in itsentirety by reference thereto for all purposes. The test temperature(§X2.1.2) may be 130° C., the sample size (§X2.1.1) may be 2 to 4 grams,and the vial purge time (§X2.1.4) may be 30 seconds. Further, the endingcriteria (§X2.1.3) may be defined as a “prediction” mode, which meansthat the test is ended when the built-in programmed criteria (whichmathematically calculates the end point moisture content) is satisfied.

Example 1

The ability to form a polymeric material for use in building insulationwas demonstrated. Initially, a blend of 85.3 wt. % polylactic acid (PLA6201D, Natureworks®), 9.5 wt. % of a microinclusion additive, 1.4 wt. %of a nanoinclusion additive, and 3.8 wt. % of an interfacial modifierwas demonstrated. The microinclusion additive was Vistamaxx™ 2120(ExxonMobil), which is a polyolefin copolymer/elastomer with a melt flowrate of 29 g/10 min (190° C., 2160 g) and a density of 0.866 g/cm³. Thenanoinclusion additive was poly(ethylene-co-methyl acrylate-co-glycidylmethacrylate) (Lotader® AX8900, Arkema) having a melt flow rate of 5-6g/10 min (190° C./2160 g), a glycidyl methacrylate content of 7 to 11wt. %, methyl acrylate content of 13 to 17 wt. %, and ethylene contentof 72 to 80 wt. %, the internal interfacial modifier was PLURIOL® WI 285Lubricant from BASF which is a Polyalkylene Glycol Functional Fluids.The polymers were fed into a co-rotating, twin-screw extruder (ZSK-30,diameter of 30 mm, length of 1328 millimeters) for compounding that wasmanufactured by Werner and Pfleiderer Corporation of Ramsey, N.J. Theextruder possessed 14 zones, numbered consecutively 1-14 from the feedhopper to the die. The first barrel zone #1 received the resins viagravimetric feeder at a total throughput of 15 pounds per hour. ThePLURIOL® WI285 was added via injector pump into barrel zone #2. The dieused to extrude the resin had 3 die openings (6 millimeters in diameter)that were separated by 4 millimeters. Upon formation, the extruded resinwas cooled on a fan-cooled conveyor belt and formed into pellets by aConair pelletizer. The extruder screw speed was 200 revolutions perminute (“rpm”). The pellets were then flood fed into a signal screwextruder heated to a temperature of 212° C. where the molten blendexited through 4.5 inch width slit die and drawn to a film thicknessranging from 0.54 to 0.58 mm.

Example 2

The sheet produced in Example 1 was cut to a 6″ length and then drawn to100% elongation using a MTS 820 hydraulic tensile frame in tensile modeat 50 mm/min.

Example 3

The sheet produced in Example 1 was cut to a 6″ length and then drawn to150% elongation using a MTS 820 hydraulic tensile frame in tensile modeat 50 mm/min.

Example 4

The sheet produced in Example 1 was cut to a 6″ length and then drawn to200 elongation using a MTS 820 hydraulic tensile frame in tensile modeat 50 mm/min.

The thermal properties of Example 1-4 Were then determined. The resultsare set forth in the table below.

Upper Lower Heat Mean Sample Surface Surface Sink Sample Thermal ThermalThermal Thickness Temp. Temp Temp Temp Resistance AdmittanceConductivity Example (mm) (° C.) (° C.) (° C.) (° C.) (m²K/W) (W/m²K)(W/mK) 1 0.58 40.5 30.0 11.3 35.3 0.0032 312.5 0.180 2 0.54 40.5 26.410.3 33.5 0.0054 185.2 0.100 3 0.57 40.5 26.1 10.3 33.3 0.0057 175.40.100 4 0.56 40.5 25.1 10.0 32.8 0.0064 156.3 0.087

Example 5

Pellets were formed as described in Example 1 and then flood fed into aRheomix 252 single screw extruder with a LID ratio of 25:1 and heated toa temperature of 212° C. where the molten blend exited through a Haake 6inch width s cast film die and drawn to a film thickness ranging from39.4 μm to 50.8 μm via Haake take-up roll. The film was drawn in themachine direction to a longitudinal deformation of 160% at a pull rateof 50 mm/min (deformation rate of 67%/min) via MTS Synergie 200 tensileframe with grips at a gage length of 75 mm.

Example 6

Films were formed as described in Example 5, except that the film wasalso stretched in the cross-machine direction to a deformation of 100%at a pull rate of 50 mm/min (deformation rate of 100%/min) with grips ata gage length of 50 mm.

Various properties of the films 5-6 were tested as described above. Theresults are set forth below in Tables 1-2.

TABLE 1 Film Properties Percent Void WVTR Average Expansion VolumeDensity (g/m²*24 Thickness (μm) Ratio (φ) (% V_(v)) (g/cm³) hrs.) 5 41.41.82 45 0.65 5453 6 34.0 2.13 53 0.56 4928

TABLE 2 Tensile Properties Avg. Avg. Avg. Avg. Energy Avg. Avg. YieldBreak Strain per Volume Thickness Modulus Stress Stress at Break atBreak Example (μm) (MPa) (MPa) (MPa) (%) (J/cm³) 5 MD 44.5 466 41.4 36.954.6 16.8 CD 40.4 501 15.9 15.9 62.6 9.4 6 MD 37.3 265 26.7 26.3 85.515.8 CD 34.3 386 25.1 25.2 45.8 9.3

Example 7

Pellets were formed as described in Example 1 and then flood fed into asignal screw extruder heated to a temperature of 212° C., where themolten blend exited through 4.5 inch width slit die and drawn to a filmthickness ranging from 36 μm to 54 μm. The films were stretched in themachine direction to about 100% to initiate cavitation and voidformation. The morphology of the films was analyzed by scanning electronmicroscopy (SEM) before and after stretching. The results are shown inFIGS. 5-8. As shown in FIGS. 5-6, the microinclusion additive wasinitially dispersed in domains having an axial size (in machinedirection) of from about 2 to about 30 micrometers and a transversedimension (in cross-machine direction) of from about 1 to about 3micrometers, while the nanoinclusion additive was initially dispersed asspherical or spheroidal domains having an axial size of from about 100to about 300 nanometers. FIGS. 7-8 show the film after stretching. Asindicated, pores formed around the microinclusion and nanoinclusionadditives. The micropores formed around the microinclusion additivegenerally had an elongated or slit-like shape with a broad sizedistribution ranging from about 2 to about 20 micrometers in the axialdirection. The nanopores associated with the nanoinclusion additivegenerally had a size of from about 50 to about 500 nanometers.

Example 8

The compounded pellets of Example 7 were dry blended with anothernanoinclusion additive, which was a halloisite clay masterbatch(MacroComp MNH-731-36, MacroM) containing 22 wt. % of a styreniccopolymer modified nanoclay and 78 wt. % polypropylene (Exxon Mobil3155). The mixing ratio was 90 wt. % of the pellets and 10 wt. % of theclay masterbatch, which provided a total clay content of 2.2%. The dryblend was then flood fed into a signal screw extruder heated to atemperature of 212° C., where the molten blend exited through 4.5 inchwidth slit die and drawn to a film thickness ranging from 51 to 58 μm.The films were stretched in the machine direction to about 100% toinitiate cavitation and void formation.

The morphology of the films was analyzed by scanning electron microscopy(SEM) before and after stretching. The results are shown in FIGS. 9-12.As shown in FIGS. 9-10, some of the nanoclay particles (visible asbrighter regions) became dispersed in the form of very smalldomains—i.e., axial dimension ranging from about 50 to about 300nanometers. The masterbatch itself also formed domains of a micro-scalesize (axial dimension of from about 1 to about 5 micrometers). Also, themicroinclusion additive (Vistamaxx™) formed elongated domains, while thenanoinclusion additives (Lotader®, visible as ultrafine dark dots andnanoclay masterbatch, visible as bright platelets) formed spheroidaldomains. The stretched film is shown in FIGS. 11-12. As shown, thevoided structure is more open and demonstrates a broad variety of poresizes. In addition to highly elongated micropores formed by themicroinclusions (Vistamaxx™), the nanoclay masterbatch inclusions formedmore open spheroidal micropores with an axial size of about 10 micronsor less and a transverse size of about 2 microns. Spherical nanoporesare also formed by the nanoinclusion additives (Lotader® and nanoclayparticles).

Various tensile properties (machine direction) of the films of Example 1and 2 were also tested. The results are provided below in Table 3.

TABLE 3 Avg. Avg. Avg. Avg. Strain Energy Avg Avg. Yield Break at perThickness Modulus Stress Stress Break Vol. Example (μm) (MPa) (MPa)(MPa) (%) (J/cm³) 1 49 2066 48.1 35 236 73 2 56 1945 41.3 36 299 85

As shown, the addition of the nanoclay filler resulted in a slightincrease in break stress and a significant increase in elongation atbreak.

Example 9

The ability to form fibers for use in building insulation wasdemonstrated. Initially, a precursor blend was formed from 91.8 wt. %isotactic propylene homopolymer (M3661, melt flow rate of 14 g/10 at210° C. and melting temperature of 150° C., Total Petrochemicals), 7.4wt. % polylactic acid (PLA 6252, melt flow rate of 70 to 85 g/10 min at210° C., Natureworks®), and 0.7 wt. % of a polyepoxide. The polyepoxidewas poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (LOTADER®AX8900, Arkema) having a melt flow rate of 6 g/10 min (190° C./2160 g),a glycidyl methacrylate content of 8 wt. %, methyl acrylate content of24 wt. %, and ethylene content of 68 wt. %. The components werecompounded in a co-rotating twin-screw extruder (Werner and PfleidererZSK-30 with a diameter of 30 mm and a L/D=44). The extruder had sevenheating zones. The temperature in the extruder ranged from 180° C. to220° C. The polymer was fed gravimetrically to the extruder at the hoperat 15 pounds per hour and the liquid was injected into the barrel usinga peristaltic pump. The extruder was operated at 200 revolutions perminute (RPM). In the last section of the barrel (front), a 3-hole die of6 mm in diameter was used to form the extrudate. The extrudate wasair-cooled in a conveyor belt and pelletized using a Conair Pelletizer.

Fiber was then produced from the precursor blend using a Davis-Standardfiber spinning line equipped with a 0.75-inch single screw extruder and16 hole spinneret with a diameter of 0.6 mm. The fibers were collectedat different draw down ratios. The take up speed ranged from 1 to 1000m/min. The temperature of the extruder ranged from 175° C. to 220° C.The fibers were stretched in a tensile tester machine at 300 mm/min upto 400% elongation at 25° C. To analyze the material morphology, thefibers were freeze fractured in liquid nitrogen and analyzed viaScanning Electron Microscope Jeol 6490LV at high vacuum. The results areshown in FIG. 13-15. As shown, spheroidal pores are formed that areelongated in the stretching direction. Both nanopores (˜50 nanometers inwidth, ˜500 nanometers in length) and micropores (˜0.5 micrometers inwidth, ˜4 micrometers in length) were formed.

Example 10

Pellets were formed as described in Example 1 and then flood fed into asingle screw extruder at 240° C., melted, and passed through a melt pumpat a rate of 0.40 grams per hole per minute through a 0.6 mm diameterspinneret. Fibers were collected in free fall (gravity only as drawforce) and then tested for mechanical properties at a pull rate of 50millimeters per minute. Fibers were then cold drawn at 23° C. in a MTSSynergie Tensile frame at a rate of 50 mm/min. Fibers were drawn topre-defined strains of 50%, 100%, 150%, 200% and 250% After drawing, theexpansion ratio, void volume and density were calculated for variousstrain rates as shown in the tables below.

Length Diameter Volume Initial Initial Initial after after after LengthDiameter Volume Strain elongation elongation elongation (mm) (mm)(mm{circumflex over ( )}3) % (mm) (mm) (mm{circumflex over ( )}3) 500.1784 1.2498  50.0  75 0.1811 1.9319 50 0.2047 1.6455 100.0 100 0.20513.3039 50 0.1691 1.1229 150.0 125 0.165  2.6728 50 0.242  2.2998 200.0150 0.1448 2.4701 50 0.1795 1.2653 250.0 175 0.1062 1.5502

Void Initial Voided Strain Poisson's Expansion Volume Density Density %Coefficient Ratio (%) (g/cc) (g/cc) Observation  50 −0.030 1.55 35.3 1.20.78 No necking 100 −0.002 2.01 50.2 1.2 0.60 No necking 125   0.0162.38 58.0 1.2 0.50 No necking 150   0.201 1.07  6.9 1.2 1.12 necking 175  0.163 1.23 18.4 1.2 0.98 fully necked

Example 11

Fibers were formed as described in Example 10, except that they werecollected at a collection roll speed of 100 meters per minute resultingin a drawn down ratio of 77. Fibers were then tested for mechanicalproperties at a pull rate of 50 millimeters per minute. Fibers were thencold drawn at 23° C. in a MTS Synergie Tensile frame at a rate of 50mm/min. Fibers were drawn to pre-defined strains of 50%, 100%, 150%,200% and 250%. After drawing, the expansion ratio, void volume anddensity were calculated for various strain rates as shown in the tablesbelow

Length Diameter Volume Initial Initial Initial after after after LengthDiameter Volume Strain elongation elongation elongation (mm) (mm)(mm{circumflex over ( )}3) % (mm) (mm) (mm{circumflex over ( )}3) 500.057  0.1276  50.0  75 0.0575 0.1948 50 0.0601 0.1418 100.0 100 0.06090.2913 50 0.067  0.1763 150.0 125 0.0653 0.4186 50 0.601  0.1418 200.0150 0.058  0.3963 50 0.0601 0.1418 200.0 150 0.0363 0.1552 50 0.059 0.1367 250.0 175 0.0385 0.2037

Ex- Void Initial Voided Strain Poisson's pansion Volume Density Density% Coefficient Ratio (%) (g/cc) (g/cc) Observation  50 −0.018 1.53 34.51.2 0.79 1 small neck ~1 mm in length 100 −0.013 2.05 51.3 1.2 0.58 2small necks approximately 5 mm in length 150   0.017 2.37 57.9 1.2 0.51No visible necking—fiber looks to be uniform 200   0.017 2.79 64.2 1.20.43 Average diameter taken from necked and unnecked region 200   0.1981.09  8.6 1.2 1.10 Diamter only taken from necked region 250   0.1391.49 32.9 1.2 0.81 Fully necked

Example 12

Fibers were formed as described in Example 10, except that the blend wascomposed of 837 wt. % polylactic acid (PLA 6201 D, Natureworks®), 9.3wt. % of Vistamaxx™ 2120, 1.4 wt. % Lotader® AX8900, 3.7% wt. % PLURIOL®WI 285 and 1.9% hydrophilic surfactant (Masil SF-19). The PLURIOL® WI285and Masil SF-19 were premixed at a 2:1 (WI-285:SF-19) ratio and addedvia injector pump into barrel zone #2. Fibers were collected at 240° C.,0.40 ghm and under free fall.

Example 11

Fibers were formed as described in Example 12 except that they werecollected at a collection roll speed of 100 meters per minute resultingin a drawn down ratio of 77. Fibers were then tested for mechanicalproperties at a pull rate of 50 millimeters per minute. Fibers were thencold drawn at 23° C. in a MTS Synergie Tensile frame at a rate of 50mm/min. Fibers were drawn to pre-defined strain of 100%. After drawing,the expansion ratio, void volume and density were calculated as shown inthe tables below,

Diam- Length eter Volume Initial after after after Initial Diam- Initialelon- elon- elon- Ex- Length eter Volume Strain gation gation gationample (mm) (mm) (mm{circumflex over ( )}3) % (mm) (mm) (mm{circumflexover ( )}3) 14 50 0.0626 0.1539 100.0 100 0.0493 0.1909

Void Inital Voided Poisson's Expansion Volume Density Density ExampleCoefficiant Ratio (%) (g/cm³) (g/cm³) Observation 14 0.2125 1.24 19.41.2 0.97 Localized necking throughout

Example 14

Fibers from Example 12 were stretched in a MTS Synergie Tensile frame ata rate of 50 meters per minute to 250% strain. This opened up the voidstructure and turned the fiber white. A one inch sample was then cutfrom the stressed, white area of the fiber. The new fiber was thentested as described above. The density was estimated to be 0.75 gramsper cubic centimeters and the pull rate for the tensile test was 305mm/min.

Example 5

Fibers from Example 11 were heated in an oven at 50° C. for 30 minutesto anneal the fiber.

Example 6

Fibers from Example 11 were heated in an oven at 90° C. 90° for 5minutes to anneal the fiber and induce crystallization.

The fibers of Examples 10-16 were then tested for mechanical propertiesat a pull rate of 50 millimeters per minute. The results are set forthin the table below.

Strain Energy Peak Peak at to Ex- Diameter Load Stress Break BreakTenacity Density ample (μm) (g_(f)) (Mpa) (%) (J/cm{circumflex over( )}3) (g/g) (g/cm³) Control 207.8 217.06  62.8  3.8  0.8 0.57   1.25PLA Fibers 10 184.6 126.65  47.3 484.5 154.0 0.44   1.20 11  62.2  22.57 73.1 464.1 205.1 0.69   1.20 12 128.5  70.32  53.2 635.3 216.0 0.50  1.20 13  59.1  16.17  57.8 495.8 184.4 0.55   1.20 14 108.5  92.95101.3 110.8  71.2 1.49 ~0.75 15  67.5  24.48  66.9 467.7 195.2 0.63  1.20 16  62.6  19.55  62.2 351.0 154.4 0.59   1.20

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

1-44. (canceled)
 45. Building insulation for use in a residential orcommercial building structure, wherein the building insulation includesa porous polymeric material that is formed from a thermoplasticcomposition containing a continuous phase that includes a matrixpolymer, and further wherein a microinclusion additive and nanoinclusionadditive are dispersed within the continuous phase in the form ofdiscrete domains, wherein a porous network is defined in the materialthat includes a plurality of nanopores having an average cross-sectionaldimension of about 800 nanometers or less.
 46. The building insulationof claim 45, wherein the polymeric material exhibits a water vaportransmission rate of about 300 g/m²-24 hours or more, thermalconductivity of about 0.40 watts per meter-kelvin or less, and/orhydrohead value of about 50 centimeters or more.
 47. The buildinginsulation of claim 45, wherein the microinclusion additive includes apolyolefin.
 48. The building insulation of claim 45, wherein thenanoinclusion additive includes a polyepoxide.
 49. The buildinginsulation of claim 45, wherein the microinclusion additive constitutesfrom about 1 wt. % to about 30 wt. % of the composition, based on theweight of the continuous phase.
 50. The building insulation of claim 45,wherein the nanoinclusion additive constitutes from about 0.05 wt. % toabout 20 wt. % of the composition, based on the weight of the continuousphase.
 51. The building insulation of claim 45, wherein thethermoplastic composition further comprises an interphase modifier. 52.The building insulation of claim 45, wherein the porous network furtherincludes micropores having an average cross-sectional dimension of fromabout 0.5 to about 30 micrometers.
 53. The building insulation of claim52, wherein the aspect ratio of the micropores is from about 1 to about30.
 54. The building insulation of claim 45, wherein the microinclusionadditive is in the form of micro-scale domains and the nanoinclusionadditive is in the form of nano-scale domains, wherein the micro-scaledomains have an average cross-sectional dimension of from about 0.5 toabout 250 micrometers and the nano-scale domains have an averagecross-sectional dimension of from about 1 nanometer to about 500nanometers.
 55. The building insulation of claim 45, wherein theinsulation is formed entirely from the polymeric material.
 56. Thebuilding insulation of claim 45, further comprising an additional layerof material.
 57. The building insulation of claim 45, wherein theinsulation is in the form of a panel.
 58. The building insulation ofclaim 45, wherein the insulation is in the form of a wrap.
 59. Thebuilding insulation of claim 45, wherein the total pore volume of thepolymeric material is from about 15% to about 80% per cubic centimeter.60. The building insulation of claim 45, wherein nanopores constituteabout 20 vol. % or more of the total pore volume of the polymericmaterial.
 61. The building insulation of claim 45, wherein thecontinuous phase constitutes from about 60 wt. % to about 99 wt. % ofthe thermoplastic composition.
 62. The building insulation of claim 45,wherein the matrix polymer includes a polyester or polyolefin.
 63. Thepolymeric material of claim 45, wherein the polymeric material is a filmor a layer of a film.
 64. The polymeric material of claim 45, whereinthe polymeric material is a fibrous material or a layer or component ofa fibrous material.
 65. A building structure comprising a buildingenvelope that defines an interior, the building structure furthercomprising the building insulation of claim 45, which is positionedadjacent to a surface of the building envelope, the interior, or acombination thereof.
 66. The building structure of claim 65, wherein thebuilding insulation is positioned adjacent to a surface of the buildingenvelope.
 67. The building structure of claim 65, wherein the buildinginsulation is positioned adjacent to an exterior wall, roof, or acombination thereof.
 68. The building structure of claim 67, wherein thebuilding insulation is also positioned adjacent to an exterior covering.69. The building structure of claim 65, wherein the building insulationis positioned adjacent to a surface of the interior.
 70. The buildingstructure of claim 65, wherein the building insulation is positionedadjacent to an interior wall, floor, ceiling, door, or a combinationthereof.